Intelligence and Miscellaneous Articles, 241 



needs, it is true, further investigation ; but that the molecules are in 

 fact directed by a current which traverses the bar, follows especially 

 from the circumstance, that on striking an iron bar through which a 

 current has been previously transmitted, a current in the same direc- 

 tion is produced. — Berliner Berichte, July 1865. 



ON THE HEAT OF FRICTION. 

 BY PROF. JOSIAII P. COOKE, J UN. 



An accident to one of the large turbine-wheels employed by the 

 Merrimack Manufacturing Corporation of Lowell has furnished a 

 most remarkable illustration of the modern mechanical theory of 

 heat ; and through the kindness of Mr. Isaac Hinckley, the accom- 

 plished agent of the Corporation, I have the pleasure of bringing the 

 facts to the notice of the Academy. I cannot do better than to 

 begin by reading Mr. Hinckley's own statement in a letter addressed 

 to me, dated December 30th, 1864. The specimens referred to in 

 the letter I have placed on the table for the inspection of the 

 Academy. 



•' In accordance with your request, I herewith send you five pieces 

 of metal once portions of one of our turbines. I have placed these 

 pieces in the box in the same relative position which they occupied 

 when they made a part of the turbine. To make my statement 

 clear to you, I would refer to pi. 1 of Mr. Francis's admirable work, 

 * Lowell Hydraulic Experiments,' which you will find in the College 

 Library. Our turbines are similar to the Tremont turbines therein 

 shown. 



"The turbine, of which these pieces were a part, is one of 250- 

 horse-power under a fall of 32 feet, using 75 cubic feet of water per 

 second. The wheel is of 58g inches diameter, with depth of float 

 of 6 inches, and a velocity of 144 revolutions per minute. Its posi- 

 tion is horizontal, and at a level of 3 feet below the surface of Mer- 

 rimack River at its ordinary stage. It is mounted upon a vertical 

 wrought-iron shaft 25 feet long and 6 inches diameter at smallest 

 place. This shaft is fitted at its upper end with a series of disks by 

 means of which it is supported in its box, which is again supported 

 by a massive cast-iron frame. This frame supports the entire weight 

 of the wheel and shaft. The shaft at its lower end is bored in the 

 line of its axis to a depth of 5|- inches to receive a steel pin of 17 j 

 inches in length and 2±- inches in diameter, and which projects from 

 the shaft 12 inches. The steady-pin has no function to perform 

 other than that of restraining the shaft from lateral aberration. It 

 is free to revolve in a box made of three pieces of case-hardened 

 iron so placed in a cast-iron frame as to allow free play to the 

 steady-pin and the free access of water to it. Each of these three 

 pieces composing this box is kept up to its place by following- 



