SciEyTiFic Lectures. 65 



long distances to wooden vessels, where it is desired to boil water. 

 Steam is the most wonderful vehicle for transporting heat with which 

 we are acquainted. This hall is heated by steam from a boiler in the 

 cellar, giving us 1,000 degrees of heat, the latent heat of the steam 

 becoming sensible as it is condensed in the pipes, and with such 

 astonishing rapidity that it sufficiently warms the atmosphere of the 

 room, furnishing one of the most efficient means of heating which is 

 known. Heating either by hot water or by steam, the relative merits 

 of which 1 am not now discussing, is by far the most economical, the 

 most efficient, and the most agreeable of all artificial means. [Prof. 

 S. then exhibited a toy steam engine, rated at two-mouse power 

 [laughter], proceeded to give an explanation of the steam engine as 

 invented by "Watt.] The first step of improvement was to close the 

 cylinder at the upper end ; hitherto it had been open. In the former 

 steam-engine the steam had forced up the piston, and upon the con- 

 densation of the air in the piston by cold the atmospherical pressure 

 brought it back again. Watt had introduced other improvements, 

 among which were the indicator, the governor, and the cut-off. There 

 has never been in the history of inventions since the world began 

 any machine or apparatus which was so perfect as it left the hands 

 of the inventor as the steam-engine was when it left the hands of 

 "Watt. You may stand to-day beside the most stupendous piece of 

 steam engineering in the world, and you will see connected with it no 

 essential change from his invention. It is true that he had no machinery 

 or tools competent to reach the exact results that w^e can now 

 produce. He had no turning-lathes, boring machines, planing 

 machines, but all was done by a cold chisel, the hammer, the file, &c.; 

 and the marvel is that he produced such results as he did. I have 

 often thought with what delight that great man would stand upon 

 one of our first-class steam frigates, or by one of our first-class 

 pumping engines, such as is used at the reservoirs in Brooklyn and New 

 York, and see the perfection, the finish, and the smoothness of the 

 work, a result possibly solely due to the genius of "Watt, because 

 without that power we could not have had the apparatus with which 

 to apply it. [Prof. S. next proceeded to illustrate the irregular expan- 

 sion of water near the freezing point. He filled a vessel with water 

 at 55 deg., and surrounded it with ice and salt to reduce its tempera- 

 ture.] A freezing mixture is composed of two solids having an affinity 

 for each other, but which cannot unite without becoming fluid ; and 

 in order to become fluid a large amount of latent heat is required, 

 [Ltst.] 5 



