2j8 The W^est American Scientist. 



The capacity of the tank is therefore a Httle over five hundred 

 and ninety-three gallons. 



Take another. A milk-pan is 14 inches across the top, 10 inch- 

 es across the bottom, and 3 inches deep; how many quarts will it 

 , contain? y 



^--^ftj} — ^- 109X3=327 



S^t/^S' 327 X -0045 ^/i=i.4824=No. of pals. 

 f //^ti" 1. 4824X4=5. 9296=No. of qts. 



Hence the pan will hold nearly six quarts of milk. If the result 

 is desired in cubic inches it may easily be obtained by multiplying 

 the number of gallons by 231. 



^'( A knowledge of the actual capacity of tanks is often very desir- 

 able, and in this easy way mere guesses may be verified, and dis- 

 putes may be settled. 



Should any of my young friends, who are mathematically in- 

 clined, be unable to find the reasons for this short rule, I shall be 

 pleased to correspond with them. Josiah Keep, 



Mills' College, Cal. 



DESCRIPTION OF A NE W HEMILENCA. 



Hemilenca Californica, n. s. Expanse, 5 , 2.40 — 2.50; ? , 2.85 

 — 2.90. 



Head, black. Antennae; 5 ., stem, brown, pectinations black; 

 ? , wholly brown. 



Prothorax, white. Patagia, white in front, overlaying longer 

 hairs of white and black. 



Thorax, black, with tufts of rust-red hairs behind the patagia. 



Abdomen, black, with a few scattered white hairs toward anal 

 end, and with white or sometimes yellow hairs in segmental spots 

 on sides beneath; 6 with large anal tuft of rust-red hairs, ? with- 

 out red tuft, but tip is hoary with short hairs of sordid white. 



Legs, femoral, with long, red and black hairs; tibiae, with fewer 

 hairs of black and white. 



Wings, above and beneath the same ; costa, dense black to apex, 

 base, dense black becoming thinner, outer margin black, sub-dia- 

 phanous, intermediate portion white, sub-diaphanous. When 

 quite fresh, the wings are clear white and black, and rather 

 opaque, but, with exposure, become sordid, yellowish and more 

 diaphanous. Veins, all are honey-color. 



Discal spots, thin, black, touching costa, but separated from 

 black base, and yet more widely from dark margin ; at the cross- 

 vein, in hs center, is the lunule. narrow, obtuselv angled, the an- 



