Identifier: workofprac00algegroundrich (find matches)
Title: The groundwork of practical naval gunnery; a study of the principles and practice of exterior ballistics, as applied to naval gunnery, and of the computation and use of ballistic and range tables
Year: 1917 (1910s)
Authors: Alger, Philip Rounseville, 1859-1912 United States. Naval Academy, Annapolis. Dept. of Ordnance and Gunnery Ingalls, James M. (James Monroe), 1837-1927
Subjects: Ballistics
Publisher: Annapolis, Md., The United States Naval Institute
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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the necessity foraccurate observations and records. Nothing is more disastrous than carelessnessin regard to details, as inaccuracy in any one of the apparently minor points mayeasily result in rendering the results of the whole practice entirely worthless. Suchinaccuracies may readily be of such a nature that they cannot be detected, and mightlead to confident entry into battle or target practice with a battery with which it isimpossible to do good work owing to the undiscovered carelessness or inaccuracy ofsome person charged with some of the duties in regard to the observations takenduring the calibration practice.Plotting of 356. Suppose we have four shots fired from a single gun, which fell as follows obs**rv6d n points of relative to the foot of the perpendicular from the center of the bulls eye upon the fall. water No, 1 a yards over a yards to the right. No. 2 h yards short V yards to the left. No. 3 c yards over c yards to the right. No. -i d yards short d yards to the left.
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Figure 33 357. Then their points of fall are as shown in Figure 33, in which we have givena projection in the vertical plane through the line of fire and the center of the bullseye, and also the corresponding projection upon the horizontal plane of the water.T is the target, the center of the bulls eye being at B, which is h feet above the water.LL is the line of sight such that the gun pointer looking along it sees the crosswires of the telescope on the center of the bulls eye. Now if the gun were in perfect CALIBEATION OF SINGLE GUNS AND A SHIPS BATTERY 219 adjustment when fired, its shot would travel along the trajectory X, pierce the bullseye at B and strike the water at P. Note that the recorded errors are actually observedfrom the point B on the surface of the water vertically below B. Therefore we haveto reduce our observations to the point P, by subtracting for overs in range, the dis-tance BP from the recorded range, and by adding the same distance for shorts; andBP may there

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