250 Wisconsin Academy of Sciences^ Arts and Letters. 



■000030, and French glass .000026. In using either of these fractions for 

 primitive crust rock the margin of error is doubtless not large. 



Deschani-ll says the compressioQ for glass per atmosphere is about 

 ,0000029. Using for apparatus the moon and Mars instead of Oersted's 

 Piezometer in experiment on the moon's crust and the crust of Mars, in- 

 st^ad of on a piece of glass, I find crust rock material is compressed 

 .0000037 per atmosphere. To one understanding the conditions, the results 

 disagree within the limits of a good corroboration of the reliability of the 

 apparatus. 



Using for expansion .00003, and for compression .0000037, the computed 

 temperature at 127 miles below the surface of the earth is about 3600° C. 

 Per observations near the surface the increase in temperature is about one 

 degree Centigrade in 90 feet, or 58 degrees in a mile. The average temper- 

 ature of the crust, then, can not be far from 2500" C. The crust, then, in 

 ■cooling to zero would contract about seven and one half per cent. This 

 would make the density or specific gravity of crust rock about 3.20. 



Ly ell's table for " Analysis of Minerals most abundant in Volcanic and 

 Hypogene Rocks," gives the following specific gravities: Hornblende- 

 Faymont, in diorite, 3.20; Hornblende-Etna, in volcanic, 3.01; Uralite Ural, 

 3.14; Angite-Bjhemia, 3.35; Angite- Vesuvius, in lava, 3.25; Diallage-Hartz, 

 n Gabbro, 3.23; Hypersthene-Labrador, 3.39; Bronzite-G eenland, 3.20, 

 Olivite Carlsbod, in basalt, 3.40; Olivite-Mt. Somma, 3.33. The metals are 

 developments from the disintegrated portion of the primitive crust. Duly 

 considered in all directions it seems not unreasonable that crust rocks have 

 a specific gravity of 3.20 at zero Centigrade. 



32. The interior density and temperature of the moon. 



The moon is admitted to be the direct and the only satellite offspring of 

 the earth, and under ihe accepted law of its evolution, positive evidence is 

 required to prove its component materials in like proportions, to vary from 

 those of the earth. The mean density of the moon is about three fifths 

 that of the earth, or 3.38 times that of water. In accordance wiih the 

 method used in computing the interior density of the earth, to keep up a 

 suitable degree of consistency and harmony with known facts, a crust or 

 outside layer density of 3.20 must be used. If the mean density, 3.38, be 

 a trifle small, or the surface density, 3.20, a little large, the remedy is to 

 increase the factor .0000037 for compression, or to freeze the moon to 100 

 ■or more degrees below zero. As the factor .0000037 satisfies the conditions 

 of Mars, that factor should not be changed. The freezing out process, 

 then, is the only antidote. Computation gives the center density of the 

 moon 3.52. The compression for a twenty-seven miles crust, or for about, 

 2,320 atmospheres, is .0086, or .0000037 per atmosphere. 



It may be that the water and the air of the moon, chemically, have not 

 yet wholly found quiet resting places, and here and there in its interior 

 •chemical action is generating heat. Dou'^^tless, however, the moon, to 

 the center, is solid, practically dead and colder than ice. 



