L. MECHANICS AND ENGINEERING. 473 



the requisite corrections, so that we may be able to foretell 

 how much the range will be increased or diminished by the 

 wind, and what allowance should be made in the direction of 

 the projectile to the right or left. The results of Major Mait- 

 land's observations are of value to others besides military 

 authorities, inasmuch as they give a means of determining 

 the velocity of the wind at considerable elevations above the 

 ground. The theoretical investigations given by him depend 

 perhaps too much upon the assumption that the pressure of 

 the wind against the projectile is inversely as the square of 

 the velocity of the wind, according to the formula of Svveaton. 

 But the actual observations quoted by him form an accept- 

 able contribution to our knowledge on this subject. A wind 

 whose velocity is estimated at twenty miles an hour pro- 

 duces, according to his observations, a deviation of thirty- 

 eight feet in a range of two miles, the diameter of the pro- 

 jectile being six and a quarter inches. 



THE BRAYTOX READY MOTOR. 



Mr. Bray ton has lately brought before the public a gas-en- 

 gine, in which sixty pounds' pressure may be generated with- 

 in the space of one minute, and which can be started by the 

 application of a match with almost the facility that gas may 

 be lighted. In construction this new motor, which has lately 

 figured in the proceedings and discussions of several of our 

 Mechanics' Institutes, closely resembles the steam-engine ; its 

 cylinder and piston, valve-gear, and connections being essen- 

 tially the same. The principal difference consists in the ad- 

 dition of a compressing-pump and a reservoir, for the purpose 

 of compressing and of retaining a quantity of combustible 

 gases, mixed with a proper proportion of air for its complete 

 combustion, and at a pressure exceeding that wdaich it is pro- 

 posed to have exerted in the working cylinder. A "jacket" 

 surrounds the cylinder, through which water is kept con- 

 stantly circulating. The comparatively low temperature 

 thus secured in the walls of the cylinder allows of the em- 

 ployment of the piston with packing rings which has become 

 the standard for the steam-engine, and likewise of the same 

 method of lubrication. A diaphragm similar to that which 

 gives the Davy safety -lamp its security, and composed 

 of several layers of wire-gauze, is placed at the opening 



