1835.] Improvements in Science. 107 



according to the determination of Colonel Hall and M. 

 Salaza, during the whole year is 15 0, 5 (59°9 F,) which 

 corresponds exactly with the results of Selaza, obtained by 

 placing the thermometer 1 foot under the surface. Boussin- 

 gault from these, and a few additional instances concludes, 

 that at least, between the 11° N. L., and 5° S. L., this 

 method of ascertaining the mean temperature holds good. 



The mean temperature of the shores in the neighbour- 

 hood of the equator, has been a subject of discussion. 

 Humboldt fixed upon 27°5 (81°5 F.) Kirwan 29° (84°2.) 

 Brewster 28°2 (82°7.) Atkinson 29°2 (84°5,) as the tem- 

 perature of the equator. Hall and Boussingault again, 

 have found the temperature of the torrid zone to vary 

 between 26° (78°8 F) and 28°-5 (83°3 F.) I consider these 

 facts too important to be overlooked, and am happy in 

 being able to communicate to travellers such a simple, 

 and at the same time, so apparently correct a method of 

 ascertaining the mean temperature of intertropical places. 

 In connexion with this subject we may consider the 



Temperature of Springs. (Pogg. Ann. xxxi. 365.) — Arago 

 remarked that the increase of the temperature of the earth 

 might be estimated by the depth of springs. Spasky 

 considers that the value of this increase may be deter- 

 mined with accuracy. From his observations on the springs 

 of Vienna he has drawn this equation, 



T = A + ax 

 in which T is the observed temperature, A the (unknown) 

 temperature on the surface, a the depth, and x the increase 

 of temperature for 1 foot in depth. As the value of each 

 observation depends on the quantity of water delivered by 

 each well in 24 hours, each equation must be multiplied 

 with this quantity of water. The general expression there- 

 fore is mT = m A + m a x 

 where m represents the quantity of water in 24 hours. 



For Vienna Spasky gives 



A = 8-0311. 

 x = 0*0117716. 

 Mean error of A 008601. 

 Mean error of x 0*00065. 



Mean temperature of the atmosphere 8° 2 R. The value 

 of a; being found, we obtain 85 feet, or less than 27 metres 

 for increase in the depth for each degree of Reaumur. 



