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THE RESISTANCE OF AIR TO THE MOTION OF

PROJECTILES.

Translated from the Italian in the Rivista di Artiglieria e Genio, January, 1896.

SECTION ONE.

During the past fifteen years there have appeared several treatises and pamphlets on ballistics, which resemble one another to the extent of following the method of the four functions introduced by us in 1880, but which are not all agreed in regard to the expressions for the resistance of the air adopted for the numerical calculation of these four functions. We made use of the Russian and English experiments (Mayevski and Bashforth); that is to say, of the formulas laid down by Mayevski in his treatise of 1872, modifying them slightly. Mitcham (West Point 1881), Ingalls (Fort Monroe, Va., 1883), De la Llave (Madrid 1883), Pouchelon (Paris 1885), Duran y Loriga (Corunna 1882), Ollero (Madrid 1890), and Holmberg (Stockholm 1895), adopted the same formulas. But Ingalls afterwards (1889) employed formulas based exclusively upon the experiments of Bashforth; and Greenhill and Hadcock (Woolwich 1887) also made use exclusively of these experiments. Hojel the distinguished and lamented author of the Dutch experiments, naturally employed the formulas devised by himself (Amsterdam 1883),-formulas which were afterward adopted by De la Llave (1893), and by Valliers (Paris 1894). Mayevski (Essen 1883 and Berlin 1886), laid down and used new formulas deduced from the Meppen firings, and was followed by Madsen (Copenhagen 1888), and by Zabouski (St. Petersburg 1895).

This diversity is easily explained by the different degrees of confidence reposed by the various authors in the experiments. It is true that in adopting the English and Russian experiments (1880), we experienced no embarrasment in making a selection. And afterwards, although sorely tempted by Hojel's experiments, which are indeed excellent both as regards the number of shots employed (about 1400) and the accuracy with which they were computed, we nevertheless adhered to the old formulas, although abandoned, perhaps unjustly by Mayevski himself; this because we satisfied ourselves that with the aid of the usual coefficient of Journal 45.

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