452 On the Rate of Increase of Underground Temperatures. 



age amount of scheelite in the vein, as a whole, but the high 

 density of the tungstate renders its separation from quartz by 

 mechanical dressing an easy matter, and suggests this as a val- 

 uable resource for tungstic acid, the value of which in the form 

 of sodic tungstate, for fire-pro. >' .. is we ll un- 



derstood. Locality. — Charity Mine, Warren's, Idaho Territory. 



My correspondent says : " The miners on this ledge (lode) 

 lately struck a pocket of ore similar to that I send, and in a 

 few evenings pounded out in a hand mortar about one thousand 

 dollars, gold value, from a few candle boxes full of ore. The 

 ore usually pays about twenty dollars per ton." 



The affinities of mineral association indicate that cassiterite 

 and wolfram may reasonably be looked for in the future explor- 

 ation of this interesting vein. " 



Since writing the above, I have learned of another and much 

 more interesting example of the occurrence of gold in scheelite, 

 from Golden Queen Mine, Lake Co., Colorado. The gold is in 

 minute crystalline granules in the scheelite and fills what 

 appears to have been a geode of scheelite crystals. 

 JSew Haven, April 19, 1877. 



Art. LIL— Ninth Report of the British Association Committee, 

 appointed for the purpose of investigating the Rate of Increase 

 of Underground Temperature downward in various Localities of 

 Dry Land, and under Water ; drawn up by Prof. EVERETT, 

 Secretaiy of the Committee.* 



A remarkable series of observations have recently been 

 taken in a boring at Sperenberg, near Berlin. The bore was 

 carried to the depth of 4,052 Ehenish (or 4,172 English) feet, 

 and was entirely in rock salt with the exception of the first 

 283 feet, which were in gypsum with some anhydrite. The 

 observations were taken under the direction of Herr Eduard 

 Dunker, of Halle-an-der-Saale, and are described by him in a 

 paper occupying thirty-two closely printed quarto pages (206- 

 238) of the Zeitschrift fur Berg-Hutten-und-Salinen-Wesen 

 (xx Band, 2 und 3 Lieferung, Berlin, 1872). 



The instrument employed for measuring the temperature was 

 the earth-thermometer of Magnus, which gives its indications 

 by the overflowing of mercury, which takes place when the 

 instrument is exposed to a higher temperature than that at 

 which it was set To take the reading it was immersed in 



* The committee consisted of Prof. Everett, Sir 1 



3 Glaisher L George 

 Foster, Prof!" 



. Pengelly, J>rof. Hull, Prof. Ansted, Prof. Prestwick, Dr. C. Le Neve 

 \ G. A. Lebour, and A. B. Wynne. 



