22 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the presence of the thermo-couples it was difficult to move the block 

 from the furnace to the cooling bath. This difficulty was avoided by- 

 counterpoising the furnace and bath so that either could be brought 

 to the block. The cooling bath was arranged to slide up and down, 

 being guided in this movement by two vertical rods. The depth to 

 which the block was submerged was regulated by fastening a clamp on 

 one of the guiding rods. The furnace was counterpoised on an arm which 

 could turn about a single guiding rod and thus be brought beneath 

 the block. With this arrangement, the block could be transferred from 

 the furnace to the bath as quickly as it could if the block were mov- 

 able. The cold junction of both couples were kept at the temperature 

 of melting ice by means of an ice-bath /, Figure 9. 



Variation in the rate of cooling. — Variation in the rate of cooling 

 was provided as follows: For rapid cooling, the block of copper was 

 surrounded by ice-water to within one centimeter of the top. For the 

 next slower rate the block was dipped in warm water to a depth of one 

 centimeter. The next slower rate was obtained by surrounding the 

 block with oil. A still slower rate was given by setting the copper 

 block on a block of iron that was surrounded by water. The next 

 slower rate was given by allowing the block to cool in air. Finally, 

 the slowest rate was obtained by allowing the block to cool in the 

 furnace. The rate of cooling was thus varied from about half a minute 

 to over two hours. 



Need for the research recorded in this paper became apparent to the 

 author upon attempting to study the magnetic properties of some 

 weakly magnetic alloys. The two difficulties which the paper dis- 

 cusses were at once encountered, and had to be overcome before the 

 work could proceed. These difficulties have been largely overcome, and 

 the road noAv seems to be fairly clear to a large and much neglected 

 field of research. 



Jefferson Physical Laboratory 

 Cambridge, Mass. 



