US2466093A - Apparatus for determining ordnance parallax correctional factors - Google Patents

Description

2 Sheets-Sheet 1 Filed Sept. 22,

INVENTOR 7fanniba2 OFOrR TTORNEYS w moo 3 umoum H/ m I I m 25 3 O Z :3 III m '1 n; m 26m m3 3 s- RCH mom April 5, 1949. H. c. FORD APPARATUS FOR DETERMINING ORDNANCE PARALLAX CORRECTIONAL FACTORS Filed Sept. 22, 1928 2 Sheets-Sheet 2 INVENTOR BY Hannibal QFo'Tfl d 5* 7 j! AZORNEYs Patented Apr. 5, 1949 APPARATUS FOR'DETERMINING ORDNANCE PARALLAX CORRECTIONAL FACTORS Hannibal C. Ford, Jamaica, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application September 22, 1928, Serial No. 307,757 Renewed February 26, 1934 12 Claims. (Cl. 23561.5)

This invention relates to apparatus for determining certain correctional factors involved in the firing of ordnance, more particularly ordnance used against aerial targets.

The invention is particularly intended for use in systems in which guns or the like are controlled from instruments known as directors which transmit to the guns indications of the train and elevation required for properly aiming them. In the case of a gun located at an appreciable distance from the director there is an angular difference between a line from the gun to the target and the line of sight from the director to the target. In practice the gun will be aimed along a line differing in both train and elevation from the line between it and the target to allow for the curvature of the trajectory of the projectiles and the effect of other factors, such as their time of flight, wind, drift and the like, all of which will be ignored as they do not enter into the parallax correction which depends solely upon the distance between the director and the gun, the angular relation between the target and the line joining the director and the gun and the range of the target.

It is accordingly necessary for accurate firing to apply to the indications of train transmitted from the director to the gun a horizontal parallax correction, as it is usually called, to compensate for the error due to the distance between the director and the gun in a horidontal plane. If there be any appreciable distance between the director and the gun in a vertical plane it is also necessary to apply a vertical parallax correction to the indications of gun elevation transmitted from the director to the gun.

Both of these corrections have been applied, either singly or jointly as required, in systems for controlling the firing of ordnance used against.

surface targets. In the case of aerial targets, however, a further vertical parallax correction is required due to the horizontal distance between the director and the gun as the line representing this distance does not lie in the same plane in which the line from the gun to the target lies, as is the case with surface targets.

It is accordingly an object of this invention to provide apparatus for determining the correction required for the accurate aiming of a gun in elevation from a director by calculating the vertical parallax due to the vertical distance between the director and the gun and the vertical parallax due to the horizontal distance between the director and the gun and correcting the gun elevation in accordance with these two quantities to give the required elevation for accurate pointing of the gun against an aerial target insofar as parallax errors are concerned.

It is a further object of the invention to pro- V vide in connection with both horizontal and vertical parallax corrections and for both surface and aerial targets an apparatus for determining such corrections by computing the values of the parallax corrections due to unit base length and converting these values to the required values by multiplying them by the ratio of the actual base length to the unit base length.

One form of apparatus which may be employed for these purposes consists of an instrument for computing the parallax correction due to a unit horizontal base length and converting this value into the required correction by multiplying it by the ratio of the actual horizontal base length to the unit horizontal base length and transmitting to the gun the indications of train corrected in accordance with the required parallax correction.

The invention further comprises mechanism in the instrument for computing the vertical parallax corrections due to both horizontal and vertical unit base lengths and converting these values into the required vertical parallax corrections by multiplying them by the ratios of the actual horizontal and vertical base lengths to the unit horizontal and vertical base lengths. The instrument also combines the vertical parallax corections due to a horizontal base and to a vertical base and corrects the indications of gun elevation transmitted from the director in ac cordance with such parallax correction in order that the gun may be accurately pointed.

The particular nature of the invention as well as other objects and advantages thereof will appear most clearly from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a diagram used in deriving the equations solved by the apparatus of the invention;

Fig. 2 is a simplified diagram of one form of apparatus in which the invention may be embodied;

Fig. 3 is an enlarged perspective view of the yielding driving mechanism of Fig. 2; and

Fig. 4 is a diagram similar to and showing parts of some of the elements of Fig. 2 but with a different form of operating mechanism.

Referring to Fig. 1, the point D represents an observing station or director located at a unit distance Uv above the plane of reference, usually a horizontal plane, in which a gun is located at the point G lying at a unit distance UH from a point A directly below the director D. The point T represents an aerial target, the range R of which from the director is therefore represented by the line DT. C represents a point in the reference plane below the target, the line TC being perpendicular to the plane and parallel to the line DA. The line AC represents the direction of the point C from the director so that the external angle GAC measured in a clockwise direction represents the bearing of the point C from A referred to the base line UH, this angle being designated B for convenience in future reference.

The line GJ represents a line from the point G perpendicular to the line AC and its length is represented by UH sin B. The portion of the line AC between A and J is represented by UH cosine B.

JK is a line from the point J to the line AT perpendicular to the latter and since in practice the portion K--T of this line is relatively great compared with the portion AK and differs but slightly from the distance D-T or R, the portion K--T may be assumed to be equal to R.

The line DM is a line parallel to the line AC at a distance Uv from the latter. The angle TDM, therefore, represents the elevation of the line of sight from the director D to the target measured relative to the line DM which is parallel to the reference plane. For convenience this angle TDM will be designated Ev. Since the range of the target is relatively great as compared with the distance Uv the angle TAC may be regarded as approximately equal to Ev.

The length of the line JK is accordingly represented by UH cos B sin Ev. The angle JTK is, therefore, approximately U cos B sin E R which represents the vertical parallax due to the unit base UH. For convenience this unit parallax factor will be designated VPUH.

DN is a line from the point D perpendicular to the line AT. The angle DAN is therefore equal to 90Ev so that the length of the line DN is Uv sin (90-Ev) or Uv cos Ev. The angle DTA is therefore approximately U cos E which represents the vertical parallax due to the unit base Uv and for convenience this unit parallax factor will be designated VPUV. The total unit parallax correction in a plane perpendicular to the reference plane, this correction being in the vertical plane when the reference plane is horizontal, will be designated VPUHV and is equal to VPUH -VPU The angle CGT represents the actual elevation of the line from the gun to the target with respect to the reference plane, or in other words, the elevation which must actually be given to the gun to allow for vertical arallax, all other factors being neglected. That is, this angle is equal to the algebraic sum of the angle Ev and the total parallax correction angle VPUHV.

Since the portion of the line AC lying between J and C is relatively great in practice as compared with the portion lying between A and J, it may be assumed equal to R cos Ev without appreciable error. Since the line GJ is represented by UH sin 3 the angle GCJ is approximately equal to U sin'B R cos E this angle being the unit parallax correction in the plane of reference due to the unit base UH and for convenience it will be designated HPUH.

The angle FGC represents the actual bearing of the line from the gun to the target with respect to the base line UH, or in other words, the bearing which must actually be given to the gun to allow for horizontal parallax. That is, this angle is equal to the algebraic sum of the angle B and the parallax correction angle HPUH.

In Fig. 2 there is shown in diagrammatic form an instrument for calculating the quantities derived from Fig. 1. It will be understood that all the parts while shown diagrammatically are in practice mounted upon a member I rotatably mounted upon a pedestal 2 within an annular rack 3 fixed to the top of the pedestal. Meshing with the rack 3 is a pinion 4 on a shaft 5 suitably mounted upon the member I and carrying a gear 6 meshing with a pinion 1 on the lower end of a shaft 8, the upper end of which carries a bevel gear '9 meshing with a corresponding gear ID on the end of a shaft ll. Meshing with the gear I0 is a bevel gear l2 on the lower end of a shaft l3 which is connected by a pair of bevel gears l4 with a shaft 15 which is connected by bevel gears l6, shaft I1 and bevel gears l8 to a pair of hand wheels l9 adapted to be operated by the trainer of the instrument to follow the movement of a target as viewed by him through a telescope 20 suitably mounted to turn in train with the member l and in elevation about an axis represented by a shaft 2| parallel to the member I. A dial 22 reading against a fixed index 23 to give indications of train or bearing B of the target with respect to the base line UH of Fig.1, is mounted at the end of a shaft 24 that is driven from the shaft l5 by a pair of gears 25.

The telescope 20 is moved in elevation by means of a gear 26 on the shaft 2| and meshing with a worm 21 connected by a pair of bevel gears 28 to a shaft 29 which by a pair of bevel gears 30 is connected to a worm 3| meshing with a gear 32 on the shaft 33 of a pointers telescope 34 which is suitably mounted to move in train with the telescope 20. The shaft 29 extends beyond the bevel gears 30 and is connected by bevel gears 35, shaft 36, and bevel gears 31 to a pair of hand wheels 38 adapted to be operated by the pointer of the instrument who follows the move ,ment of the target in elevation. The elevation angle Ev is indicated :by a dial 39 reading against a fixed index 40 and attached to the end of a shaft 4| which is connected by bevel gears 42 to the elevation shaft 29.

Shaft H which is rotated in accordance with the bearing angle B by the trainer is connected through bevel gears 43 to a shaft 44 carrying at one end a pinion 45 which meshes with a gear 46 meshing in turn with gear 41 which will, therefore, be turned in accordance with the angle B. Gear 41 is provided with a radial slot 48 within which is mounted a slidable block 49 carrying a rod 50, which extends through a spiral groove 5i in a gear 52 which is rotated in accordance with values of range as will now be described, the spiral groove being arranged to cause a radial movement of the rod 50 in accordance with reciprocal values of range, that is, in accordance with A crank 53 on the end of a, shaft 54 is adapted to be turned in accordance with values of range R SEARCH as received from a suitable instrument, such as a range finder. The values are indicated by a dial 55 reading against a fixed index 56 and mounted upon the end of a shaft 51 connected by bevel gears 58 to the shaft 54. The shaft 54 is also connected by bevel gears 59 to a shaft 60 having its other end connected to the center 6| of a differential 6|. One side 6|" of the differential carries a gear 62 meshing with the gear 46, so that this side of the differential receives a movement proportional to the bearing angle B as does the gear 41. The second side 6I' of the differential carries a gear 63 meshing with the gear 52. By virtue of the differential 6| the gears 41 and 52 are turned in accordance with the bearing angle B and the gear 52 receives a displacement relatively to the gear 41 in accordance with range R so that the rod 50 is positioned in accordance with bearing B and reciprocals of range The rod 50 also passes through a slotted arm of a rectangular slide 54 which, therefore, receives a movement proportional to U cos B R it being understood that the quantity Us which is a constant representing a unit length of base line is provided for by suitable proportioning of the parts. The rod 50 also passes through a slotted arm of a second rectangular slide 65 which receives a movement proportional to U sin B R The rod I2 is attached to a block I3 slidably mounted in a radial slot I4 in a gear 15 adapted to be rotated in accordance with values of the elevation angle Ev by the following elements. Meshing with the gear 15 is a pinion I6 on the end of a shaft 11 which is connected through bevel gears 18, shaft I9 and bevel gears 80 to the Ev shaft 29. The shaft I1 also carries a gear 8| meshing with a gear 82 attached to the second side 68" of the differential 68. By virtue of the differential, the gears 10' and I5 are moved in accordance with values of the angle Ev and the gear I is displaced relatively to the gear I in accordance with values of so that the rod I2 is positioned in accordance with both of these quantities. The rod 12 also extends through a slotted arm of a rectangular slide 83 which is moved in accordance with the quantity Uv cos E R The quantity Uv, which is a constant represent ing a unit length of base line is provided for in the instrument by suitable proportioning of its parts.

As shown most clearly in Fig. 3 the vertical arm of the slide 65 is provided with a rack meshing with a pinion 84 loose on a shaft 85 and having a pin 86 normally held against a pin 81 projecting from the shaft by a spring 88 attached at one end of the pinion 84 and at the other end to a collar 89 fastened to the shaft 85. A similar but reversely wound spring 90 is attached at one end to the collar 89 and at the other end to a pinion 9| also loosely mounted on the shaft 85 similarly to pinion 84. The pinion 9I carries a pin 92 normally held by the action of the spring 90 in engagement with a pin 93 attached to the shaft. The pinion 9| meshes with the larger gear of a compound gear 94, the smaller gear of which meshes with a rack on the vertical arm of a rectangular slide 95. The mechanism described in this paragraph constitutes a yielding driving connection between the slide 65 and the slide 95, the operation and purpose of which will be hereinafter explained.

Slidably mounted on the horizontal arm of the slide 95 is a carriage 96 provided with a rod 91 extending through a slot in this arm and into a slotted link 98 restrained at one end by a fixed rod 99 passing through the slot. The other end of the link is attached to a reciprocating rack I00 meshing with a pinion IOI on a shaft I02 connected through bevel gears I 03 to a shaft I04 having detachably secured to its lower end a gear I05 meshing with a gear I06 detachably secured to the upper end of a shaft I01.

It has been previously stated that the instrument computes the value of the horizontal parallax correction for a unit horizontal base length and converts this correction into the required correction by multiplying it by the ratio of the actual horizontal base length to the unit horizontal base length. Since for any particular installation the actual base length is fixed, the gears I05 and I06 perform the converting operation, their ratio being suitably selected in accordance with the ratio between actual and unit base lengths. By being detachably secured to their shafts they may be readily changed to adapt them to different installations with different ratios.

The shaft I0! is connected through bevel gears I08 to the side I09 of a differential I09, the center I09 of which is attached to a shaft IIO connected by bevel gears II I to a shaft II2 for actuating a transmitter I I3 of any suitable type for sending training indications to the controlled gun. The shaft II 2 drives through bevel gears II4, shaft 5 and bevel gears II6, a dial II'I reading against a fixed index I I9 to show the values of the indications transmitted to the gun, so that if the transmission system fails indications can be obtained and sent to the gun by other means.

The other side I09 of the differential I09 carries a pinion ||9 meshing with a gear I20 on the other end of the shaft 44 which as previously explained receives a movement proportional to the bearing angle B from the trainer's hand wheel I9.

The shaft 29 is connected through bevel gears I2I, shaft I22 and bevel gears I23 to the side I24" of a differential I24. This side also carries a pinion I25 meshing with a gear sector I26, which thus receives from the shaft 29 an angular movement proportional to the elevation angle Ev. The gear sector carries a rod |2I extending rearwardly into a slotted arm of an inverted U-shaped slide I28 which receives a movement proportional to cos Ev from the gear sector I26. The other slotted arm of the slide receives the forwardly extending portion of the rod 91. Since as previously described the slide 65 receives a movement proportional to U Sill B R the slide 95 receives through the yielding driving connection consisting of the elements designated 84 to 90, both inclusive, a corresponding movement.

Under normal conditions of operation the spring 88 holds the pins 86 and 81 in engagement so that the movement imparted to the gear 84 by the slide 05 is transmitted through the shaft 85 and the pins 93 and 92 which are held in engagement by the spring 90 as if the shaft con.- stituted a rigid connection between the pinions. Under usual conditions and for consistent values of the movements of the slide 95 representing and slide I28 representing cos Ev, the relation of the slides, pin 91 and link 98 will be such as to cause a movement of rack I with no possibility of disengagement of the rack from pinion IOI. In practice stops will be provided for limiting the movement of the rack to prevent such disengagement, but when this is done there is a possibility when the instrument is operated for unusual and inconsistent values of the quantities UH Sill B R and cos Ev that the rack I00 will reach one 01' the other of its stops before the slides have reached positions corresponding to those required by the conditions under which the instru-.

ment is being operated.

When this occurs the movement of slide 95 is prevented through the pin 9! and link 98 connected to the rack I00, the movement of which has been stopped. The slide 65 may however continue to move because one or the other of the springs 88 or 89 will be placed under increased tension to permit separation of the pins 86 and 81 or 92 and 93 according to the direction in which the gear 84 is being turned by the slide 65 after movement of the gear 9I has been prevented by the stopping of slide 95 which is connected to the gear by the compound gear 94. The springs 88 and 90 are so designed that while under normal conditions of operation they hold the pins 86 and 81 on the one hand and the pins 92 and 93 on the other hand in engagement, they will yield and permit separation of the pins before there is any danger of damage to any of the elements of the instrument by continued movement of slide 65 after the rack I00 has reached its limits of movement.

As previously explained the slide 95 receives a movement proportional to U sin B R and the slide I28 receives a movement proportional to cos Ev. These slides are so related as to displace through the rod 91 and link 98 the rack I00 in accordance with the quantity UH sin B R cos E 8 This movement is transmitted to the pinion IOI, shaft I02, bevel gears I03 and shaft I04, to the gear I05 which in conjunction with the gear I06 multiplies this quantity by the ratio of the actual base length Ln to the unit base length UH to give the quantity LH UH Sill B U R cos E L; sin B R cos E which is the horizontal parallax correction HPn due to the actual horizontal base length Ln. This quantity is reproduced in the movement of the side I09 of the differential I09 throughthe shaft I0! and bevel gears I08. Since, as previously explained, the other side I 09" receives a movement proportional to the bearing angle B from the trainers hand wheels, the center I 09 receives a movement proportional to the algebraic sum of the bearing angle and the horizontal parallax correction, that is, BiHPL The resultant movement of the centre of the differential causes through shaft IIO, bevel gears III and shaft IIZ a corresponding actuation of the transmitter I I3 to send to the gun indications of the required train corrected for horizontal parallax. At the same time the measure of this quantity is carried from shaft II2, by bevel gears II I, shaft H5 and bevel gears II6 to the dial II! where the indication of the quantity is read against its index II 8.

It has previously been explained that the slide 83 is moved in accordance with the quantity The horizontal arm of this slide is provided with a rack which meshes with a pinion I 29 on a shaft I30 connected through bevel gears I3I, shaft I32 and bevel gears I33 to a shaft I34 having detachably secured to its upper end a gear I35 meshing with a gear I36 detachably secured to the lower end of a shaft I31. These gears perform the function of converting the quantity which represents the vertical parallax due to the unit base Uv into the vertical parallax due to the actual base Lv, their ratio being proportional In other Words, they multiply the quantity U cos E R by the ratio Lv UV giving L cos E R blliliibil EiUUit't extends forwardly into the slotted arm of a U-shaped slide I4I the other slotted arm of which receives the rear end of a rod I42 projecting from a carriage I43 slidably mounted on the vertical arm of a rectangular slide I44, the arm being slotted to permit the passage through it of the rod. The horizontal arm of this slide is provided with a rack meshing with a pinion I45 on a shaft I46 to which is detachably secured a gear I41 meshing with a gear I48 detachably secured to the side I40" of the differential I40. As previously explained slide 64 receives a movement proportional to U cos B R U cos B sin E ,which is the vertical parallax correction VPu due to the unit horizontal base line UH. The gears I41 and I48 have a ratio proportional to UH the same as the gears I and I06 and they multiply the quantity U cos B sin E is. UH giving LH cos B sin E; R

which is the vertical parallax correction VlF'r. due the actual horizontal base Ln.

Since the centre I40' of the differential I40 receives a movement proportional to the vertical parallax correction due to the actual vertical base Lv and the side I40" receives a movement proportional to the vertical parallax correction due to the actual horizontal base Ln, the other side I40 receives a movement proportional to the algebraic sum of these corrections, that is, VPn iVPr. or VPLHV the total vertical parallax correction. This side is rigidly connected to the side I24' of differential I24 of which the center I24 is connected to a shaft I5I, which thus receives a movement proportional to the elevation angle Ev through the side I24" and the total vertical parallax correction VPLHV through side I24 of the differential, the movement of the shaft thus representing the elevation indication which should be transmitted to the gun as corrected for vertical parallax, or nvivm This is accomplished by a drive from the shaft I 5I through bevel gears I52, shaft I53, bevel gears I54, shaft I55, bevel gears I56, shaft I51, bevel gears I58 and shaft I59 of a transmitter I60 connected to a suitable receiver at the gun. The shaft I55 also drives through bevel gears I6I and shaft I62, a dial I63 reading against a fixed index I64 to give indications of the corrected elevation being transmitted to the guns for use in case the transmission system fails and it is necessary to convey the information by other means.

In Fig. 4 is shown a modified form of operating connection between the slides 65 and 95 and the rack I00. In this arrangement, the slide 65 of Fig. 2 drives through pinion 84, shaft I66, and pinion I61 a pinion I68 on the side I69 of a diiferential I69. The other side I69 of the differential carries a pinion I10 meshing with a pinion I1I on a shaft I12 which is connected through a pair of pinions I13, shaft I14 and pinion I15 with a gear I16 having integral therewith the compound gear and pinion 94 meshing with the rack of the slide 95.

The center I69 of the differential is attached to a shaft I18 which carries a cam I19 having substantially semi-circular portions of unequal radii. The cam operates a contact device I of the general type shown in more detail in my Patent No. 1,577,618, granted March 23, 1926, for Speed regulating mechanism. In the normal condition of the device, its roller I8I engages an intermediate cam portion between the dwells of the cam I19 and the contact arm I82 of the device lies midway between fixed contacts I83 and I84. The contact arm has a portion insulated from the rest of the device and electrically connected by a conductor I85 to the positive main I86 of a source of supply. The contacts I83 and I84 are connected by a conductors I81 and I88 respectively to the reversely wound field windings of a motor I89 of any suitable type and the circuit is completed through its armature and then by a conductor I90 leading to the negative main I9I. The motor drives through shaft I92 and pinion IOI the rack I00 corresponding to the similarly designated rack of Fig. 2. The shaft I92 also drives through bevel gears I94 shaft I04 of Fig. 2.

In the operation of this modification of the invention the movement of slide 65 is transmitted through pinion 84, shaft I66 and pinions I61 and I68 to the side I69" of difierential I69. Regarding its other side I69 as fixed since it is connected to the slide 95, the center I69 will be turned to turn the cam I19 by shaft I18. This will actuate the contact device I80 to shift its arm I 8-2 into engagement with one or the other of the contacts I83 or I84 according to whether the roller I8I moves outwardly or inwardly as a result of the turning of the cam. A circuit is, therefore, established from the main I86 through conductor I85, arm I82, one or the other of the contacts I83 or I84 and the conductor I81 or I88 connected thereto, the corresponding field winding of the motor I89, the armature of the motor and conductor I90 leading to the other main I9I. Through shaft I92 and pinion IOI the motor moves the rack I00 to position the link 98 and rod 91 that are shown in Fig. 2. The movement imparted to the rod displaces the slide 95 and through the compounded pinion and gear 94, pinion I15, shaft I14, pinions I13, shaft I12, pinions HI and I10, the side I69 of the diiferential will be displaced. Regarding the other side I69" as now fixed, the center I69 will be displaced, but in the opposite direction to its former displacement to oppositely turn the cam I19 to restore the contact device I80 to its normal position and open the circuit of the motor I89.

The elements above described constitute a follow-up system by which the movement of slide 65 is reproduced at slide 95 and the corresponding movement of the rack I is also produced, as in the case of these same elements described in connection with Fig. 2. If under unusual and inconsistent values of the quantities involved the rack I00 reaches one of its stops before the slide 65 reaches its required position the motor will be stopped, but the cam I19 will continue to turn without offering any appreciable resistance to the movement of the slide 65, so that there is no danger of damage to any of the elements of the instrument. In other words, the modification shown in Fig. 4 performs the function of the yielding driving connection of Figs. 2 and 3 but has the advantage over such a mechanical drive in that additional power from the motor is obtained for operating the elements of the instrument. When the slide 65 again reaches a position corresponding to consistent values of the quantities involved the motor will again become effective to actuate the rack Hill as above described.

While the invention has been described in connection with an aerial target it is equally adapted for controlling ordnance used against surface targets. In this case the angle Ev is zero and there is no vertical parallax due to the base UH, but only that due to the base Uv and the horizontal parallax due to the base UH. In other words, the expression U cos B sin E R representing the vertical parallax due to the base UH becomes zero. In other respects the invention is the same and the instrument operates as described in connection with an aerial target.

While certain preferred embodiments of the invention have been described, it will be understood that it may be embodied in other forms and that various changes in structural details may be made without departing from the principle of the invention as defined in the appended claims.

I claim:

1. In an instrument for determining an angular correctional factor depending on a, plurality of variables, the combination of means for computing the value of the factor for unit value of one of the variables and means for multiplying the value of the factor by the ratio between the actual value of the variable and the unit value thereof said second mentioned means being detachably associated with said first mentioned means to allow for altering of the multiplying ratio when the ratio between the actual value of the variable and unit value thereof is altered.

2. In an instrument for determining a parallax correction the combination of means for computing the value of the correction for a unit base length and means for multiplying the value of the correction by the ratio between the actual base length and the unit base length, said multiplying means being detachably associated with said com- .puting means to provide for altering the multiplying ratio to conform with the ratio between the actual base length and unit base length.

lar relation of an object with respect to'a base line lying in a reference plane and between two separated points from one of which the angular relation is known, the combination of means for determining the angular relation corresponding to a unit length of the base line between the points including an element displaceable in accordance with a function of the known angular relation of the object, a secondelement displaceable in accordance with a function of the distance of the object from the point from which the angular relation is known, means for combining the displacements of the members, a third element displaceable in accordance with a function of the angular relation of the object with respect to the reference plane, and means for combining the movements of the first combining means and the third element, means for multiplying the movement of the second combining means by the ratio of the actual length of the line between the points to a unit length of said line and means for correcting the known angular relation of the object in accordance with the correctional alteration of the angular relation as determined by the last named means.

5. In an instrument for determining a parallax correction, the combination of means for determining the parallax correction due to a unit length of the base line between two points including an element displaceable in accordance with a function of the bearing of a distant object from one of the points, a second element displaceable in accordance with a function of the range of the object, means for combining the displacements of the members, a third element displaceable in accordance with a function of the angle of elevation of the object and means for combining the movements of the first combining means and the third element and means for multiplying the movement of the second combining means by the ratio between the actual length of the base line and the unit length thereof.

6. In an instrument for determining a parallax correction, the combination of means for determining the parallax correction due to a unit length of the base line between two points including an element displaceable in accordance with a function of the elevation of a distant object, a second element displaceable in accordance with a function of the range of the object and means for combining these displacements of the members, and means for multiplying the movement of the combining means by the ratio between the actual length of the base line and the unit length thereof.

'7. In an instrument for determining the hearing of an object from one of two separated points from the other of which the bearing is known, the combination of means for determining the parallax corrections due to a unit length of the base line between the points including an element displaceable in accordance with a function of the bearing of the object, a second element displaceable in accordance with a function of the range of the object, means for combining the displacements of the members, a third element displaceable in accordance with a function of the angle of elevation of the object and means for combining the movements of the first combining means and the third element, means for multiplying the movement of the second combining meansby the ratio between th actual length of the base line and the unit length ther of and means for correcting the bearing of the object from one of the points by the determined SEARCH R9959 parallax correction for the actual base length to give the bearing of the object from the other point.

8. In an instrument for deter-mining a parallax correction, the combination of means for determining the parallax correction due to a unit length of the base line between two points including an element displaceable in accordance with a function of the elevation of a distant object, a second element displaceable in accordance with a function of the range of the object and means for combining the displacements of the members, and means for multiplying the movement of the combining means by the ratio between the actual length of the base line, and the unit base length, means for determining a second parallax correction due to a unit length of a second base line between one of said two points and a third point including an element displaceable in accordance with a function of the bearing of the object, a second element displaceable in accordance with the range of the object, means for combining the displacements of the members, a part displaceable in accordance with a function of the angle of elevation of the object and means for combining the movements of the second combining means and the part, means for multiplying the movement of the third combining means by the ratio between the actual length of the second base line and the unit length thereof, and means for combining the movements of the two means for determining parallax corrections to give the total parallax corrections.

9. In an instrument for determining the angular relation of an object with respect to a base line lying in a reference plane and between two separated points from one of which the angular relation is known, the combination of means for determining the angular relation corresponding to a unit length of the base line between the points including an element displaceable in accordance with a function of the known angular relation of the object, a second element displaceable in accordance with a function of the distance of the object from the point from which the angular relation is known, means for combining the displacements of the members, a third element adapted to be displaced in accordance with the combined displacements of the elements, a yielding driving connection between the combining means and the third element, a fourth element displaceable in accordance with a func-- tion of the angular relation of the object with respect to the reference plane, and means for combining the movements of the third and fourth elements, means for multiplying the movement of the second combining means by the ratio of the actual length of the base line between the points to the unit length of said line and means for correcting the known angular relation of the object in accordance with the correctional alteration of the angular relation as determined by the last named means.

10. In apparatus for transmitting the movement of one member to another member, the combination of an element operatively connected to the first member, a part movably related to the element, means connected between the element and the part for normally holding them in fixed relation but adapted to yield to permit relative movement between them, a second element operatively connected to the second member and movably related to the part and means connected between th second element and the part for normally holding them in fixed relation but adapted to yield to permit relative movement between them.

11. In apparatus for transmitting the movements of one member to another member, the combination of a gear operatively connected to the first member, a shaft upon which the gear is movably mounted, resilient means connected between the gear and the shaft for normally holding them in fixed relation but adapted to yield to permit relative movement between them, a second gear operatively connected to th second member and movably mounted upon the shaft and resilient means connected between the second gear and the shaft for normally holding them in fixed relation but adapted to yield to permit relative movement between them.

12. In an instrument for determining training and elevational movements for a gun used against an aerial target including horizontal and vertical parallax corrections, the combination of means operable in accordance with required uncorrected movements of the gun in elevation and train, means for computing vertical parallax corrections due to vertical and horizontal unit bases, means for computing a horizontal parallax correction due to the horizontal unit base, mechanisms for multiplying the respective computed corrections by the ratios between the unit bases and the actual vertical and horizontal bases, and means for combining the vertical and horizontal parallax corrections with the required elevational and training movements effected by the first named means.

HAN'NIBAL C. FORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 714,786 Day Dec. 2, 1902 934,223 Scott Sept. 14, 1909 996,331 Hall June 27, 1911 1,135,596 Locarni Apr. 13, 1915 1,232,968 Pollen et a1 July 10, 1917 1,370,204 Ford Mar. 1, 1921 1,392,959 Meitner Oct. 11, 1921 1,419,283 Mattson June 13, 1922 1,438,832 Kaminski Dec. 12, 1922 1,453,104 Gray Apr. 24, 1923 1,487,460 Hansson Mar. 18, 1924 1,492,899 Schneider May 6, 1924 1,512,103 Kaminski Oct. 21, 1924 1,532,754 Kaminski Apr. 7, 1925 1,615,509 Grotendorst Jan. 25, 1927 1,684,315 Haller Sept. 11, 1928

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