74 



SCIENCE. 



[N. S. Vol. XVI. No. 411. 



I have never approved of elaborate steam 

 engines got up for students' laboratory 

 exercise-work. A professor ^Yho had de- 

 voted much thought for a year to the con- 

 struction of such a four-cylinder engine 

 showed a friend how any one or any two 

 or anj^ three or all four cylinders, with or 

 without jacketing, could be used in all 

 sorts of wa3-s. The friend ventured to 

 say: 'This engine will be used just once 

 and never after.' The professor was 

 angry, but his friend proved to be right. 

 The professor made experiments with it 

 once himself with a few good students. 

 Unfortunately it was not a sufficiently elab- 

 orate investigation for publication. After- 

 wards he never had time personally to 

 superintend such work ; his assistants were 

 busy at other thing-s; his students could 

 not be trusted with the engine by them- 

 selves, and to this day it stands in the 

 laboratoi'Y a beautiful b\it useless piece of 

 apparatus. At Finsbury there was an 

 excellent one-cylinder engine with vapor- 

 izing condenser. It drove the workshops 

 and electric generators. On a field-day it 

 drove an electric generator only, and per- 

 haps thirty students made measurements. 

 Each of them had already acted as stoker 

 and engine-driver, as oiler and tester of 

 the machinery, lighting fires, taking indi- 

 cator diagrams, weighing coals, opening 

 and closing cocks from seven in the morn- 

 ing to ten at night, so that everything was 

 well known to him. They maintained three 

 dift'erent steady loads for trials of three 

 hours each. They divided into groups, 

 one from each group ceasing to take a par- 

 ticular kind of observation everj' ten min- 

 utes and removing to another job. All 

 watches were made to agree, and each stu- 

 dent noted the time of each observation. 

 These observations were: Taking indicator 

 diagrams, cheeking the speed indicator, 

 taking temperature of feed-water, quantity 

 of feed by meter (the meter had been care- 



fully checked by gauge-notch, and every 

 other iustriiment used by us had been tested 

 weeks before), taking the actual horse- 

 power passing through a dynamometer 

 coupling on the shaft, taking boiler and 

 valve-chest pressures and vacuum pressures 

 on the roof and in the engine-room, weigh- 

 ing coals (the calorific value had already 

 been tested), taking the hoi*se-power given 

 out bj^ the djTiamo, counting the electric 

 lamps in iise, and so on. Each student 

 was well prepared beforehand. During 

 the next week he reduced his own observa- 

 tions, and some of the results were gath- 

 ered on one great table. One lesson that 

 this taught could never be forgotten — how 

 the energy of one pound of coal was dis- 

 posed of. So much up the chimney or by 

 radiation from boiler or steam-jacket and 

 pipes; in condensation in the cj'linder; to 

 the condenser; in engine friction; in shaft 

 friction, etc. I cannot imagine a more 

 important lesson to a young engineer than 

 this one taught through a common working 

 engine. The stiidents had the same sort 

 of experience with a gas engine. I need 

 hardly say how important it was that the 

 professor himself should take charge of 

 the whole work leading up to, during, and 

 after such a field-day. 



The difiSculty about all laboratory exer- 

 cise work worth the name is that of finding 

 demonstrators and assistants who are wise 

 and energetic. Through foolishness and 

 laziness the most beautifiil system becomes 

 an iinmeaning routine, and the more 

 smoothly it works the less ediicational it 

 is. In England just now the curse of aU 

 education is the small amount of money 

 available for the wages of teachers — just 

 enough to attract mediocre men. I have 

 been told, and I can easily imagine, that 

 such men have one talent over-developed, 

 the talent for making their job softer and 

 softer, until at length they just sit at a 

 table, maintaining discipline merely by 



