548 



MECHANICAL ENGINEERING, THE PEOGRESS OF. 



are completely at sea in respect to systems of 

 construction of large guns. Treadwell and 

 Woodbridgo have pointed out one direction of 

 progress by the application of the strongest 

 known form of metal, hard drawn steel wire, 

 in building up the barrel, and Whitworth 

 has shown what can be accomplished with 

 stoi-1 iu masses. The gun is already a heat- 

 engine of high efficiency, but thermodynamic 

 investigations show that this gas-engine may 

 bo iniitlo still more efficient. A gun in 

 which the charge expands twenty-five times 

 should give to the shot an energy of 300,000 

 foot-pounds per pound of good ordinary pow- 

 der, and such a standard must sooner or later 

 be closely approximated. As the heat is gen- 

 erated and expanded in a very small fraction 

 of a second, the gas expands adiabatically, and 

 the loss of efficiency comes from incomplete 

 expansion. The tendency of improvement is 

 to have guns lengthened greatly, and carefully 

 proportioned to their work. Recoil is consid- 

 ered to be in many cases often an avoidable 

 evil with breech-loading guns. It is expected 

 that with the improvements in progress guns 

 can be held fast against recoil, and thus the 

 defect in efficiency will be entirely avoided. 

 Increased accuracy and power with flattened 

 trajectory and reduced drift will come with 

 ti.rse improvements, and the last will give much 

 greater convenience and safety in working, and 

 will aid still more in the effort to unite guns 

 and supporting structure as closely and firmly 

 as possible. 



That feature of recent progress in engineer- 

 ing which is awakening most interest in the 

 minds of the public as well as of the profes- 

 sion is the introduction of machine-made elec- 

 tricity, and of the electric light. The prospect 

 of the use of the electro-dynamic machine as 

 a distributer of power is a more momentous 

 consideration than its use as n generator of light. 

 The mean of several series of tests of a power- 

 ful dynamo-electric machine from Menlo Park 

 gave, as a result, an efficiency of between 90 and 

 95 per cent. 



This important advance in that field in which 

 the mechanical engineer and the electrician 

 have joined hands, will lead to the probable 

 early success of the electrical railway, a prom- 

 ising scheme of simplifying the problem of 

 transportation on elevated railways; and it is 

 not unlikely that the rising generation may 

 see the introduction of this method of dis- 

 tributing power from a central source in the 

 great cities, and even from Niagara, with its 

 3,000,000 horse-power, to distant cities. The 

 competition of this method of distributing 

 light, heat, and power, with the already prac- 

 tical plan of steam distribution introduced by 

 Holly, of Lockport, and now coming into use 

 in New York city under the direction of Em- 

 ery, will be watched with unusual interest. 



The improvements in the control and appli- 

 cation of electric energy render the prospects 

 of aerial navigation far less problematical. In 



the science of aeronautics progress, although 

 slow, is still to be observed year by year. 

 During the Franco-German War the French 

 naval engineer, M. Dupuy de Lome, succeeded 

 in giving to the balloon a slow motion by 

 means of a screw, and in directing its course 

 by a rudder. His balloon was spindle- or cigar- 

 shaped, and contained 12,000 cubic feet of gas. 

 It could carry fourteen men, and the screw 

 was worked by four or eight men. But the 

 only hope of aerial navigation lies in the direc- 

 tion of flying-machines, lifted by their own 

 power, not buoyed up by gas. Men of science, 

 like Pettigrew, Marey, and De Lucy, have stud- 

 ied the motions of the wings of birds and in- 

 sects, have learn-ed the laws of fluid resistance, 

 and have paved the way to a real advance. 

 "Weight is probably not objectionable in aerial 

 navigation, but volume constitutes the impedi- 

 ment. Comparing the lady -bird, the stag- 

 beetle, the pigeon, the stork, the sparrow, etc., 

 De Lucy found the area of wing per unit of 

 weight carried to be nearly as the cube root 

 of their weights. A man of ordinary weight 

 should, therefore, be able to fly with wings hav- 

 ing an area of only about forty square feet. 

 De Villeneuve states that a bat having the 

 weight of a man would need wings only ten 

 feet long. Marey has made birds in harness 

 record graphically the motions of their own 

 wings ; and Hanghton and Marey and others 

 have determined the working power of mus- 

 cles in proportion to weight and size, and the 

 method of movement of muscles and wing. 

 Henson, Stringfellow, May, and others have 

 made self -impelling model flying -machines, 

 some of which have actually lifted themselves 

 in the air, and several of which have flown 

 with great speed when once lifted clear of the 

 ground. The most remarkable achievement 

 is that of Henson in making a steam-engine, 

 fragile to be sure, but still a working machine, 

 producing a third of a horse-power, and weigh- 

 ing less than fifteen pounds. Still, there is as 

 yet but little on which to base an expectation 

 of finding a satisfactory yet powerful motor. 



The introduction of the power-press and the 

 gradual incorporation into one automatic ma- 

 chine of the web-perfecting press of Sir Rowland 

 Hill and of Jephtha "Wilkinson's, of "Worms's cy- 

 lindrical stereotype plates, of Richard Hoe's 

 type-cylinder and double-acting fly-frame; of 

 Applegarth's enlarged impression-cylinder, and 

 of minor improvements, have led to the creation 

 of the modern printing-press. To-day a daily 

 paper can be printed at the rate of 30,000 im- 

 pressions an hour, each paper printed on both 

 sides, cut from the great roll in which it came 

 to the press, pasted in shape and folded ex- 

 actly to size, and then counted off by the ma- 

 chine as delivered to the carrier. The work 

 of the compositor is likely to be greatly accel- 

 erated by the type-setting machine, which has 

 attained extraordinary perfection. Paige's ma- 

 chine receives a column of " dead matter " 

 from the press, distributes it automatically, 



