MECHANICAL ENGINEERING, THE PROGRESS OF. 



547 



error of assuming that the condensation of 

 steam due to transmutation of heat into work 

 produces the principal part of the water ob- 

 served in the cylinders of engines working dry 

 steam, is becoming recognized. Later writers 

 hold that the greater part of the water which 

 collects in unjacketed cylinders is not produced 

 by liquefaction of steam during its expansion, 

 but that this latter amount is insignificant, and 

 that this water comes of cylinder condensa- 

 tion, sometimes with considerable leakage, and 

 often amounts to a half or more of all the fluid 

 supplied by the boiler. This defect, existing 

 in all heat-engines, will probably soon be rem- 

 edied to such an extent as no longer to consti- 

 tute the great obstacle to further advance. 

 The trials of steam-engines, now often con- 

 ducted by the Forey & Donkin method of 

 measuring the heat rejected, afford a reliable 

 means of measuring actual efficiencies. Re- 

 cently, Eckart has applied the chronoscope of 

 Hipp to the determination of the exact veloci- 

 ties of piston in mid-stroke. There is a pros- 

 pect that the precise action of steam in the en- 

 gine and the causes of variation in efficiency will 

 be better understood. The progress which has 

 been made in naval engineering during a gener- 

 ation illustrates the advances observed in nearly 

 every other department. Naval works, wheth- 

 er in the civil or the military marine, have be- 

 come almost purely the work of tha mechanical 

 engineer. The ship-builder constructs his ships 

 of iron and steel ; their lines are laid down by 

 the laws of engineering science ; their parts are 

 formed in the machine-shop and put together 

 by the same methods that are adopted in con- 

 structing their boilers. They are driven by 

 steam-engines ; and even their loading and the 

 discharge of their cargo have become matters 

 of engineering. The old-fashioned mariner is 

 rapidly disappearing, and the engineer is likely 

 to become the responsible officer on the voy- 

 age, as during construction. The daily advance 

 noticeable in naval construction is a progress 

 leading directly and rapidly toward bringing 

 all naval warfare within the province of me- 

 chanical engineering. A generation ago, the 

 French line-of-battle ship Napoleon, with her 

 100 guns and 600 horse-power engines, repre- 

 sented the most formidable of naval vessels, 

 A little later, in 1856, the American W abash 

 class of screw-frigates, with fewer but much 

 heavier guns, was thought to be the coming 

 type. Then the modern ironclad came to revo- 

 lutionize all naval warfare. The engineers Rob- 

 ert L. Stevens and John Ericsson, and the naval 

 architect Edwin J. Reed, led the way to the con- 

 struction of the war-ship of to-day, a craft car- 

 rying ordnance weighing from 25 to 160 tons, at 

 speeds varying from twelve to sixteen knots ; 

 plated with from fourteen to thirty inches of 

 armor, and yet penetrable by their own guns. 



Navies are coming to be divided into three 

 classes of ships, and an independent service of 

 torpedo-vessels: 1. A class of vessels for ser- 

 vice in time of peace, of moderate size and 



speed, carrying a few heavy guns, unarraored 

 and with great sail-power ; 2. A class of un- 

 armored ships of very high speed under steam 

 and carrying a light battery, such ships as 

 might be best calculated to destroy the com- 

 merce of an enemy ; and, 3. A class for heavy 

 fighting, carrying the heaviest of guns and the 

 most impenetrable of armor, with as high 

 steam-power as possible, and rendered, by di- 

 vision into compartments, as nearly unsink- 

 able as possible. Owing to the introduction of 

 the stationary, the floating, and the automatic 

 classes of torpedoes and of torpedo- vessels, the 

 attack by any navy of stationary defenses is 

 now quite a thing of the past ; and torpedo- 

 ships of very high speed may yet drive all 

 heavily-armored vessels from the ocean. The 

 production of such craft as the Polyphemus, 

 making seventeen knots, and Ericsson's De- 

 stroyer, with its great submarine gun, and the 

 self-propelling torpedo, guided from the shore, 

 indicate that the day of cessation of all naval 

 warfare is not far away. 



In gunnery, stronger and safer ordnance 

 metal, breech- loading in place of muzzle-load- 

 ing, increased velocity of projectile, a flatter 

 trajectory with less lateral drift, and with 

 enormously increased range, are the changes 

 now occurring. Whitworth's compressed steel, 

 Krupp's breech mechanism and skillful design 

 and construction, have given guns capable of 

 driving shot at velocities of over 1,200 feet 

 per second with small-arms, and nearly 2,000 

 feet with heavy ordnance. Whitworth, with 

 a comparatively small piece, has attained a 

 range of nearly ten miles. The machine-guns 

 of Gardner, as built by Pratt and Whitney, 

 and the Gatling and others, as constructed by 

 the Colt Company and the Ames Manufactur- 

 ing Company, firing a thousand shots a minute, 

 have rendered the old methods of warfare, in 

 which large masses of troops were deployed 

 in the open, entirely obsolete, while the accu- 

 racy of sharp- shopting at ranges of 1,000 yards 

 or more make the use of any unprotected ord- 

 nance at short ranges extremely difficult. Hol- 

 low cast guns, as made by Rodman, although 

 the best cast-iron ordnance ever known, are 

 now of the past ; and even the Armstrong, the 

 Woolwich, and other guns built up in the 

 forge, fail, when made of eighty and one hun- 

 dred tons weight, and must give place to solid 

 steel guns. Improved methods of making ex- 

 plosives and better adjustment to the work by 

 variation of composition, and especially size 

 and density of grain, has enabled artillerists to 

 keep pressures much below twenty-five tons per 

 square inch, while greatly increasing the energy 

 developed per pound burned and corresponding- 

 ly increasing the effectiveness of ordnance. The 

 theoretical energy of good powder is about 

 250,000 or 300,000 foot-pounds per pound. In 

 experiments, an actual result equal to two 

 thirds is now obtained. There is still much to 

 be done in perfecting ordnance, especially in 

 its construction, and as yet ordnance officers 



