314 



NATURE 



[August 5, 1897 



carried on in Anglesey and in the south-west of Ireland. 

 Taking the official statistics for 1895, one finds that only 

 thirteen persons were employed underground in Anglesey, 

 and thirty-two in the county of Cork. These figures 

 scarcely justify the adverb used by Prof. Louis. Herods- 

 foot mine is spoken of as if it were still at work, though 

 it was abandoned fully ten years ago ; in fact, Cornwall 

 has ceased for some time to be a lead-producing county. 

 No doubt it is easier to pick a few holes in a work 

 of this kind than to write it, and it must not be sup- 

 posed from my criticisms that I in any way undervalue 

 the great amount of care and labour which Prof. Louis 

 has bestowed upon his work. The new book is a very 

 valuable addition to technical literature, in spite of the 

 want of a sufficient number of plates, which was likewise 

 a fault of the first edition ; possibly Prof Louis may 

 have had to bow to restrictions imposed upon him by 

 his publishers. In any future edition it would be better to 

 sacrifice some of the letterpress, if by so doing more 

 figures could be introduced. C. L. N. F. 



THE RESISTANCE OF THE AIR. 

 Experiments made with the Bashforth Chronograph to 

 and the Resistance of the Air to the Motion of Pro- 

 jectiles. By Francis Bashforth, B.D. (Cambridge : 

 at the University Press, 1895.) 



IF Mr. Bashforth could have struck a bargain with the 

 Government similar to that made by James Watt 

 with the Cornish miners, his royalties on the gunpowder 

 saved annually by the use of his Ballistic Tables would 

 have rivalled the claims contested in some recent law- 

 suits. 



By a few well-designed experiments with his Electro- 

 Ballistic Chronograph, initiated now more than thirty 

 years ago, when he took up the appointment of Pro- 

 fessor of Mathematics to the Advanced Class of Artillery 

 Officers, he was able to determine the resistance of the 

 air at all useful velocities to the projectiles fired from the 

 muzzle-loading guns then in vogue, to which a return 

 had been made by our military authorities. 



In accordance with the proverb — "Otj oIk isTi Trpo^^rrjs 



StIjUOJ, 6t yU^ iv TJ) TTttTptSl aVTOV, KoX Iv TO?S (TvyyevfCTi 



Kal 4v TJ? ojKigi avrov — these experiments attracted great 

 attention in naval and continental expert circles, every- 

 where except at Woolwich ; they still remain to this 

 day the only actual determinations of the Resistance 

 of the Air with which we have to work in Artillery ; 

 and the Ballistic Tables of Mr. Bashforth, based upon 

 these experiments, are to be found in all naval and 

 foreign treatises on the Theory of Artillery. 



When the Bashforth Chronograph revealed the unsteadi- 

 ness of shooting of our guns, the manufacturers of ammu- 

 nition and guns felt insulted, and wanted to throw the 

 blame on the imperfections of the instrument, as if their 

 manufactures were not absolutely perfect ; now, how- 

 ever, in recent Range Tables, the manufacturers have to 

 submit to the indignity of 50 per cent, zones, showing the 

 degree of scattering of their weapon at the various 

 ranges. 



Although the breech-loading system has been finally 

 adopted, and although the experimental side of Elec- 

 NO. 1449, VOL. 56] 



tricity may be said to have been re-created since Mr. 

 Bashforth began to experiment, so far no new experi- 

 ments have been carried out or sanctioned for finding the 

 modification of the Resistance of the Air due to changes 

 of shape in modern projectiles, and to the superior 

 steadiness in flight obtainable with the breech-loading 

 system. 



Gunpowder, or cordite, costing annually many 

 thousands of pounds, is blazed away at proof, merely to 

 inspect brands of powder by determining a muzzle 

 velocity, by shooting between two electric screens. If 

 only one more screen, but the more the better, could be 

 introduced, much useful information could be gained at 

 the same time of the Resistance of the Air. 



The Boulenge Chronograph, employed at proof, is not 

 adapted for more than two screens; but superior Chrono- 

 graphs are now in the field, with which it is possible to 

 read any number of screen records. 



Every new Chronograph claims to record at least a 

 millionth of a second ; but Mr. Bashforth did not attempt 

 to go behind the fourth decimal, knowing that the 

 accuracy of any experiment is only that of its most 

 inaccurate part ; in this case the screens, in which the 

 breaking of a wire might take place within the limits of a 

 foot, according to the manner in which the wire is struck 

 by the head or shoulder of the projectile ; this alone is 

 sufficient to account for a discrepancy enough to render 

 the fourth decimal almost nugatory. 



By averaging the results, however, of as many rounds 

 as possible, Mr. Bashforth has arrived at the normal 

 Resistance of the Air, from which individual shots may 

 vary as much as 10 per cent, or more ; and allowing for 

 difference of shape, smoothness, and steadiness of 

 projectile, the continental experiments of Krupp and 

 others amply confirm Mr. Bashforth's results. 



Inflation in the manufacture of warlike stores is at the 

 present moment unprecedented ; and yet very little careful 

 examination takes place, of what improvements are 

 possible as the result of scientific inquiry, carried out 

 leisurely on a small scale. Our ministers vote millions 

 for warlike stores, and still, as in the days of General 

 Peel's report, they scrutinise with the greatest care a 

 small vote, technically called ineffective, which serves to 

 prevent these millions from being money thrown away. 



Provided with Bashforth's Tables, and a knowledge of 

 how to use them, which need not appreciably alter his 

 weight or the height of his centre of gravity in the saddle, 

 the artillery officer of the future might dispense with half 

 the useless weight of ammunition he drags about in the 

 field ; or, at least, the same weight might be refashioned 

 for a heavier gun, employing curved fire. 



The superior ballistic coefficient of the larger pro- 

 jectile soon enables it to overtake the puny projectile of the 

 rival pop-gun ; but to secure these advantages, good range- 

 finding is an indispensable accessory ; the weight of the 

 most efficient range-finder need not, however, exceed that 

 of a single round, which might otherwise be expended as 

 a trial shot. 



Mr. Bashforth writes occasionally with bitterness ; but 

 he has been the victim of our curious official scientific 

 etiquette, which disparages a new idea when sub- 

 mitted, and afterwards appropriates the results without 

 acknowledgment when the idea has proved a success. 



