278 METEOROLOGY AND ALLIED SUBJECTS. 



year (1.150) was 1819 ; the warmest (6.250) was 1826. {Z. 0. G. M., XVI, 

 1881, p. 492.) 



Dr. F. M. Stai>ff, geologist of the St. Gotliard railroad, has discussed 

 the observations of the temperature of the earth made by Forman in the 

 Comstock lode, Nevada. He finds that below 1,G00 feet the rate of in- 

 crease of temperature begins to diminish, and that, as we cannot safely 

 extrapolate, therefore no conclusion can be drawn as to temperatures at 

 greater depths in the earth than about 2,000 feet. As the result of year, 

 of experience in measuring temperatures of stone, Stapff estimates that 

 it would be impossible by direct observation to decide the question 

 whether or no temperatures increase in the interior of the earth. 



The delicacy of the temperature changes, the unavoidable disturbances 

 from the drill, and the irregularities due to streams of water are only 

 to be overcome by persistent study of the various sources of error. 



In the second communication Stapff gives a new formula, and shows 

 that the computed temperatures of the air at the surface, as observed 

 for twelve years, agrees with that computed trom the observed tem- 

 peratures within the mines. {Z. 0. G. if., XVI, 1881, pp. 414 and 518.) 



Buys Ballot has published (Archives Neulandaises, Tome XV) an 

 exhaustive memoir on the annual periodicity and variability of temper- 

 ature of Europe. By combining three days into one triad and tliree 

 such triads into a series of nine days' means, he studies the perturba- 

 tions in the regular annual temperature curves. By subtracting the 

 means of two triads ten days apart and dividing by 10 he obtains the 

 average rate of change of temperature for all i^ortions of the year, and 

 the average of these ten-day changes at seventeen places, for which long- 

 series of observations are available, gives him an expression for the 

 normal average periodicity of temperature in Europe, independent of 

 local disturbances, which latter can then be determined. In reference 

 to the variability of temperature. Buys Ballot attempts to properly rep- 

 resent, first, the daily variation; second, the uncertainty of the temper- 

 ature of any day of the month or year; third, the magnitude of inequal- 

 ities of long periods. Very interesting are his tables showing the ten- 

 dency of tlie weather to repeat itself in successive months ; thus, if the 

 tendency to repetition is a mere matter of chance, then the chance that 

 out of 374 months six successive months should have the same charac- 

 ter, namely, warmer or colder, then the average would be 3^, as given 

 in the second column of the following table, whereas the observed 

 number. of such months is 36, as given in the third column: 



