August 31, 1906.] 



SCIENCE. 



261 



to the consternation of the framei'S of this 

 foolish prohibition, the premium on gold 

 soared higher than ever. The result was a 

 hasty and shamefaced repeal. 



Experience of this kind is too common 

 in economic legislation. It serves as a 

 warning that we should know something 

 of economic science before venturing to 

 tamper with economic conditions. The 

 men who need this warning most of all are 

 those who despise all 'theories' and call 

 themselves 'practical.' It is they who 

 legislate a measure one day and have to 

 repeal it the next. A truly practical man 

 can predict how a measure will work, and 

 his power so to do requires not only what 

 is called 'practical' but also what is called 

 'theoretical' knowledge; a knowledge, in 

 short, not only of history but of science. 



Irving Fisher. 

 Yale Univeesity. 



SECTION D— MECHANICAL SCIENCE AND 

 ENGINEERING. 



The meetings of the section were held in 

 the lecture room of Sibley College of 

 Mechanical E^gineering and Mechanic 

 Arts, of Cornell University, on Friday and 

 Saturday, June 29 and 30. They were 

 followed by the fourteenth annual meeting 

 of the Society for the Promotion of En- 

 gineering Education, an affiliated society 

 of the association. 



In the absence of the vice-president, the 

 retiring vice-president, Fred W. McNair, 

 president of the Michigan College of Mines, 

 acted as chairman of the section. Twenty- 

 three members of the association registered 

 as belonging to the section, while members 

 of other sections attended some of the 

 meetings. Experience gained at this meet- 

 ing has shown that it is not conducive to 

 the greatest attendance to have Sunday 

 intervene between the meetings of the sec- 

 tion and of the affiliated society. 



The first two papers were by Byron B. 



Brackett, professor of physics and elec- 

 trical engineering of the Thomas S, Clark- 

 son Memorial School of Technology, Pots- 

 dam, N. Y, The first paper describes a 

 'Lamp Bank composed of Small Separate 

 Units.' Each unit consists of twelve in- 

 candescent lamps arranged in a partially 

 open box, 28 inches long and 10 inches 

 square. The boxes are open enough to 

 give perfect ventilation. On one side are 

 placed switches for cutting in or out the 

 lamps of that particular box, and for 

 changing the grouping of the lamps into 

 parallel, series or combination arrange- 

 ments. As many of these units as are de- 

 sired may be placed one upon the other in 

 tiers, and as many tiers as are needed may 

 be placed side by side to form a lamp bank 

 of any capacity. Each unit is constructed 

 to permit convenient interconnection with 

 the adjacent ones. Thus, the large bank 

 may be separated into smaller ones when- 

 ever desired and reassembled with the least 

 possible loss of time and effort for special 

 tests on large machines. 



His second paper was on an 'Alternating 

 Current Wave-form Apparatus.' 



To set the armature accurately for the 

 separate readings in, the ballistic method 

 of tracing the E.M.F. wave of an alterna- 

 tor, a double or duplicate brake apparatus 

 is unusually satisfactory. Two similar 

 clamp brakes with long arms are placed on 

 the pulley side by side. With the arms 

 held rigidly the desired readings for one 

 observation are made. Then brake No, 1 

 is undamped at the pulley, the end of its 

 arm released and rotated up a short dis- 

 tance to a fixed stop. Brake No. 1 is now 

 clamped to the pulley, brake No. 2 is un- 

 damped, the end of No, 1 turned down to 

 its original position and No. 2 is clamped 

 again. Thus the armature has been ro- 

 tated through a small angle, that may be 

 computed with great accuracy from the 

 length of the arms and the distance 



