43 



Details of (lie jjracfirnni. — 



1. With the rubber tube detached l'n>iii ;-nil tuhes, Hft tlir aspirator weight, allow- 

 ma ])ell to fall to bottom of aspirator tank. 



2. Attach rubber tube to soil tube No. 1. 



3. Now carefully lower weight until it is just sustained by jiressure of air upon 



the bell. 



4. With watch note time required for the hand to pass over three divisions of the 

 dial, recording time as indicated iii a table like the one below. 



5. In like manner attach rubber tube to Nos. 2, 3, 4, 5, 6, 7, an.l s and note and 

 record the time required to pass over three divisions of tlic dial. 



Ym. 4.— Aiii>iiiatiis ust'd to study the movumeiit of air through soils. 



(i. In like manner attach rubber tube to Nos. 9, 10, 1 1, and 12 and note tlu> time 

 required for the hand to pass over one division on the dial. Multiply this time by 

 three and introdiu^e in table. 



7. Make computations and till in as indicated in the table. 



