Progress of Invention. 151 



Thus, the steam is not only heated to the temperature it had when 

 it entered the first cylinder, and therefore has no tendency to lose 

 its vaporous form, but it is superheated, so as to have an increased 

 pressure. And this restoration of heat, and superheating, is the 

 source of the greater economy, as the heat required for the purpose 

 costs nothing, being taken from the products of combustion just 

 before they are about to escape into the chimney, and to carry off 

 and waste any heat still remaining in them. 



Combination of Horse and Steam Power for Locomotives on 

 Ordinary Roads. — The great difficulty attending the introduction- 

 of steam on ordinary roads, as far as the public is concerned, is the 

 danger of accidents of a most serious kind from the least interrup- 

 tion of attention on the part of the engineer in charge of the 

 vehicle. On a curved or crowded road there must be constant 

 changes of direction, without which collisions, or other dangerotis 

 effects, will certainly take place. With a vehicle dz-awn by horses, 

 their intelligence, not less than that of the driver, is effective ; and 

 in cases in which the driver is negligent, or even incapable, from 

 sleep, or some other cause, the horses may, and often do, bring the 

 vehicle safe through every peril. This consideration has suggested 

 the utilization of the intelligence of the horse — which, unlike that 

 of the engine-driver, is undoubtedly ever occupied only with things 

 present — by a means which M. Seguier has recently brought under 

 the notice of the Academy of Sciences. The horse is to be attached 

 to the locomotive, not for the purpose of giving the least assistance 

 in drawing the vehicle, but with the sole object of aiding in its 

 guidance : it will therefore undergo no fatigue. A shaft, which is 

 placed in front of the steam-carriage, and to which the horse is . 

 yoked, is so connected with the steam machinery, that when the 

 horse advances, the steam is turned on, when he moves back, it 

 is turned off; and when he turns to either side, the mechanism 

 required to turn the carriage in the proper direction is thrown into 

 action. 



Renovation of the Polished Surface of Glass. — Hydrofluoric 

 acid in the form of gas, and that dissolved in water, has very 

 different effects on glass. As a gas, it entirely removes the polish, 

 rendering the glass incapable of transmitting the images of objects ; 

 as an aqueous solution, it removes the old surface, without destroy- 

 ing the polish, but, on the contrary, rendering it more brilliant. 

 For this purpose a very dilute acid must be employed ; if tolerably 

 concentrated, it will eat a hole in the surface of the glass on which 

 it is placed ; bat this hole will have a brilliant appearance. This 

 property, possessed by hydrofluoric acid in solution, has suggested 

 it as an excellent material for cleaning glass which has been 

 tarnished by time or bad usage. 



Application of Electro-Magnetism to the Manufacture of Iron. 

 — It has been found by recent experiments that electro-magnetism 

 can be used with excellent effect in the manufacture of iron ; the 

 process being facilitated, and rendered more perfect, while, at the 

 same time, fuel is economized. An opening is made in the smelting 

 furnace, and opposite to this opening is placed an electro-magnet, 



