PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 611 



produced by the blow which caused the fracture, and was not the result of 

 previous tremulous motions. 



Mr. Stetson was willing to believe that the rapidity of the act might 

 greatly affect the appearance of the fractured surfaces, but agreed that the 

 doctrine would be productive of evil if carried to the extreme of supposing 

 that there were not great actual differences in the structure of metals. He 

 instanced as common the cases of axles, which after breaking showed that 

 the bars of which they had been formed were far more fibrous than others 

 piled in the same axle. The great mass of cast iron cooled some years ago 

 at the Novelty Works, before it could be poured, was broken open in the 

 slowest manner by very tapering wedges, but its interior was in large 

 crystals, and its exterior in fine. This is due to the fact that the outside 

 was cooled rapidly and the inside very slowly. The manner of breaking 

 could not have affected the molecular arrangement. 



New Drawing Rollers for Spinning Machinery. 



W. Wield, of Manchester, lately explained before the Mechanical Engi- 

 neers' Society his improvement in fluted rollers, which consists in forming 

 the flutes spirally on the r(jllers at an inclination of one in 12 to the axis of 

 the roller. The fluting is made by giving a twisting motion to the roller 

 while in the act of cutting. The diameter of rollers depends on the length 

 of the cotton fiber. The length of the New Orleans and African cotton. 

 fiber is from one inch to l|; the Brazil from one inch to 1|; the Egyptian 

 from one inch to 1^'; American Sea Island from 1| to 2| inches. The cot- 

 ton from the new sources of supply — East India and Nanking — now being 

 introduced has a much shorter length, ranging from five-eighths to one inch. 

 For the purpose of drawing this cotton, which is done Vy passing it 

 between two pairs of rollers) the second pair having a greater speed than 

 the first, it is requisite that the diameter of the rollers should not exceed 

 three^burths of an inch, in order to bring the two pairs of rollers near 

 enough together to deal with fiber five-eighths of an inch long. The lengths 

 of these rollers are from 16 to 22 inches, and they are coupled together so 

 as to extend in a right line from 30 to 120 feet, and are driven from one 

 end. Wrought iron is not satisfactorily applicable to rollers of such small 

 diameiei', for in addition to the weakness of coupling there is an amount of 

 torsion which causes the time of action to be sensibly different at the two 

 extremities. The slower delivery at one end gives an undue stretch upoa 

 the yarn and breakage is the consequence. Steel rollers will obviate the 

 difiSculty. The high price of the ordinary steel induced Mr. Wield to try 

 the Bessemer steel. It is found to be suited to this purpose. Its cost is 

 about $125 per ton. 



Utilization of Seaweed. 



Mr. E. A. Wunsh read a paper upon this subject before the Philosophical 

 Society of Glasgow, and illustrated it with chemical tables and specimens 

 of plants. He stated that about 10,000 tons of "kelp" are produced 

 annually, and that it could be produced in much larger amount if the cli- 

 mate did not interfere with the drying process. One authority estimates 

 the quantity of weed thrown up annually at 21,000,000 tons, of which not 



