Handbook of Range-finders: 70 Cm. and 80 Cm. Base for Use of Infantry and Cavalry : with Description and Instructions for Their Care and Use (Google eBook)

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U.S. Government Printing Office, 1917 - Optical range finders - 25 pages
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Page 3 - This manual is published for the information and government of the Regular Army and Organized Militia of the United States. By order of the Secretary of War; WILLIAM CROZIER, Brigadier General, Chief of Ordnance.
Page 11 - The best defined part of an object should be selected to observe upon. Coincidence should preferably be made in the center of the field of view, and, if possible, with the dividing line at right angles to the object observed. With 34 FIRE-COXTROL IXSTRrMKXTS MOBII.K.
Page 9 - P can be found varying with the distance of the observed object where the reflected ray will pass through the point D, thus meeting the ray CAD. The two coinciding images of the same prisms are so placed at the point D that they reflect the light from both ends of the range-finder into the eyelens F, and the images are actually found at a point in front of the eyelens, the position of the images depending upon the type of the instrument. Since there is a certain position of the prism P which will...
Page 25 - ... should be removed for a short time to allow a current of air to pass through the tube, but this should only be done in dry weather, never in rain or fog, or if smoke or dust is about the range-finder.
Page 9 - D'. The angle D'BD is equal to the angle C'BC" and varies with the distance of the observed object. The ray BD' could be made to take the direction of BD by revolving the reflector B, but the amount of this revolution is so small for moderate changes in range and so difficult for accurate measurement that the same result is obtained by the use of the prism P, the reflecting angle of which is very small. A position of the...
Page 9 - F, and the images are actually found at a point in front of the eyelens, the position of the images depending upon the type of the instrument. Since there is a certain position of the prism P which will bring the two halves of the object into coincidence, then a suitably graduated scale attached to the prism and moving with it will record the distance of the object corresponding to the position of the prism. In the actual range-finder various prism and lens combinations are employed in...
Page 11 - ... in range finding as in anything else accuracy increases with practice. It has been found that different observers have what might be called personal errors which diminish as their experience increases.
Page 11 - It is advisable when time permits to obtain the range by taking the mean of several consecutive readings.
Page 11 - When both edges of the object are equally well defined the observer should always make his coincidence on the same edge, right or left.
Page 10 - As the tube is liable to be distorted as a result 10523917 2 10 of the effect of temperature changes, or of handling during the working of the instrument, it...

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