576 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Mr. Hedrick inquired which of all the coals could be used with 

 the best advantage. 



Mr. Bruce said he had used all manner of coal, from the pea 

 coal up to the Lackawanna, for manufacturing purposes, and he 

 found that the Lackawanna and Lehigh were the best. All the 

 other anthracite coals had a tendency to melt the bars. 



Dr. Stevens. — All the various kinds of coal differ very much 

 in the quantity of carbon which they contain. The Lehigh coal 

 will range as high as 95 per cent of carbon. The Lackawanna 

 contains about 15 per cent of carbon. Cumberland coal is semi- 

 anthracite. Broad-top is a semi-bituminous coal, and contains 

 about 65 per cent of anthracite. The Lottsburg coals are semi- 

 bituminous. All these coals lie east of the Allegany mountains. 

 West of them a gassy coal is obtained which is used by the Man- 

 hattan Gas Co. We have a coal from Virginia which differs very 

 much from these. Red ash and white ash signifies the amount 

 of iron contained in it. It is the iron that gives it the color. 

 We get from New Brunswick the famous oil coal, — the Albert 

 coal as it is called. The price of the Albert coal is from $14 to 

 $18 a ton. The Lackawanna is furnished here at $3 a ton. 



Mr, Hedrick. — Which coal is the hardest to burn ? 



Dr. Stevens. — The Lehigh is the hardest. You cannot get any 

 coal without sulphur. 



Adjourned to Thursday evening next, February 14th, 1861. 

 Subject, " Compressed air, and its use in propulsion." 



American Institute, Polytechnic Association, ) 

 February 14, 1861. 5 



Prof. Mason in the chair. 



projectiles. 



Mr. Lewis Masquerier read a paper on " Progressive and 

 Rotary Motion." 



Can a rotatory motion have a leverage upon the progressive 

 motion of a bullet or planet, so as to deflect it from a rectilinear 

 into a curvilinear direction ? 



The aberration of balls fired from a smooth bore ordnance, is 

 said to have suggested the cutting of the spiral grooves in them, 

 by which they invariably receive a rotatory motion, around an 

 axis pointing one of its poles to the mark, and strike with more 

 certainty. If the rotatory motion can have such a deflecting 



