1886.] NEW YORK ACADEMY OF SCIENCES. 145- 



illustnition, take a coal-oil lamp and light it — and it smokes, cer- 

 tainly not from want of air, but because it cannot raise the tempe- 

 rature to ignition. Put on the chimney, limiting the air supply 

 to what can be raised to a proper temperature, and the smoking 

 ceases. 



The first table shows an analysis of the products of com- 

 bustion. Out of the 21 volumes of oxygen in 100 volumes of 

 air, in a few instances I found 17.6 united with the carbon to 

 produce carbon di-oxide. But generally the results were much 

 below, 10 to 12 volumes being about an average. In some 

 cases the consumed oxygen was only 1.5 to 3. In the latter 

 cases the waste of coal was very great, not only in the large 

 amount of cinder ejected, but in the units of heat carried 

 off by the excess of air passing through the fire-box and 

 flues. 



The second table gives the results of a series of experi- 

 ments to trace the heat units in one pound of coal utilized 

 in various locomotives. This is, as far as I know, the first of 

 its kind ever presented. Each locomotive was run on its train 

 at least 600 miles, and some were run 1,200 miles. The fuel 

 and water consumed were measured, the gases of combustion 

 analyzed, and the heat in the smoke-box measured. The head- 

 ings of the columns are sufficiently explicit to explain fully the 

 table. The striking contrasts with different locomotives show 

 that much could be saved by proper attention to the blast and 

 skilful firing. 



The locomotive is still in a transitional state; the needs of to- 

 morrow may not be met by the construction of to-day. 



Most of the wrought iron used in the early constructions came 

 from England, and also some of the locomotives. The latter 

 were not adapted for the frail structures which the scanty means 

 of a new country permitted to be built. ' 



In 1830 only 23 miles of railway were in use; in 1840, 2,818; 

 in 1850, 9,021; and in 1860, 30,635. The length constructed 

 represented the comparative ease with which the difficulties were 

 overcome. 



The first locomotives of only seven to eight tons weight would 

 draw two or three of the light passenger cars 15 to 20 miles per 

 hour. The strap rails of one-half to five-eighths of an inch 

 thick by two inches wide, laid upon the wooden stringers, after 

 short service became loose, and sometimes would curl up through 

 the car floors. There were many efforts to improve the form of 

 the rails and at the same time make them cheap. Double-headed 

 rails, continuous rails, and inverted U rails were used. Col. 

 John Stevens, then president of the Camden and Amboy Eail- 

 road, invented in 1830 the present T rail. The quality of the 



