In the spring and early summer of the present year nearly a dozen runs 

 were made. All were of a preliminary nature, the whole apparatus being 

 entirely new, and the attendents unskilled in the management of the com- 

 plicated mounting machinery. 



At the beginning of the present school year the work was taken up anew. 

 The object of the present work is. in general, to determine the perform- 

 ance of the engine under conditions varying, first, as to cut- off and, sec- 

 ondly, as to speed. To this end, five series of six-tests each have been 

 arranged, all to be run under a constant pulling load of 2500 pounds. This 

 constancy of load makes the mean effective pressure practically constant 

 for all tests, and the power developed dependent upon the speed. The 

 load lacks but little of being ecpuivalent to 10 horse-power for each mile 

 per hour of speed. 



All of the tests of the same series are run at the same speed, but each 

 test varies from the others of the series by a change in cut-oft'. The second 

 series differs from the first, and the third from the second, and so on, only 

 in a change of speed. The first series at 15 miles per hour, and the second 

 at 25 miles per hour, have already been run, and, in carrying them on, all 

 conditions were as perfectly maintained as could be desired. The remain- 

 ing series will be at 35, 45, and 55 miles per hour respectively. Every test 

 is complete in itself. The observed data include speed, drawbar stress, 

 coal and water consumption, calorimeter determination, draft and tem- 

 perature in smoke-box, and cylinder performance as obtained by the use 

 of four indicators. All tests are of three hours duration and are run with- 

 out intermediate stops or change of speed. A comparison of results, first 

 of the tests of each series, and secondly, of tests of the same cut-offin the 

 different series, cannot fail to furnish an analysis of the performance of 

 the locomotive which will be far more complete than anything hitherto 

 attempted. 



The electrostatic theory of cohesion and Van der Waal's equatk 

 By Reginald A. Fessexdex. 



Quartz suspensions. By Benj. W. Snow. 



A THERMO- REGULATOR TOR ROOMS HEATED I« STEAM. By J. C. ARTHUR. 



