236 APPENDIX 



tangular piece of brass (B). This piece of brass is ^ inch 

 high and -^ inch thick, with smooth inner surface. 



3. A piece of brass (C), same dimensions as (B), but 

 without screw holes, and not attached to base (A). 



4. A piece of brass (D,) \ inch by ^ inch by 1 inch, at- 

 tached to base (A) as shown. 



5. A piece of wood (E) t f inch by Ij inches by f 

 inch, with one edge cut to shoulder upon the piece (C) as 

 shown. 



6. A metal pin (F), ^ inch in diameter, mounted in 

 base as shown. 



7. A wooden wedge (G), 1 J inches long and f inch thick, 

 cut as shown. 



8. When the metal piece (C) is placed on the base as 

 shown, with the piece of wood (E) shouldering upon it, 

 and the wedge (G) driven into place, the metal pieces (B) 

 and (C) thus form a box 3 inches by 3 inches by \ inch 

 deep. 



These metal pieces might be made of babbit. They 

 may be made of iron but are subject to rust. If made of 

 babbit, the thickness should not be less than f inch. 



(B) To perform the experiment : 



1. Measure out 200 grams of clay soil. 



2. Place in dish and add just sufficient water to 

 moisten. 



3. Thoroughly knead, or work, until the mass has be- 

 come thoroughly mixed. 



4. It may be necessary to add more clay as the kneading, 

 or working, operation proceeds. 



5. Continue the kneading until the water has taken up 

 all the soil it will thoroughly moisten, in other words, until 

 the mass is as dense as it can be made by kneading. 



