78 Miscdlaneous. 



wanted. The simplicity and certainty of the experiinei:l l>y 

 T\hich the cold produced by the eraporation of water is nipasurc <!, 

 renders an accurate theory of the result peculiarly desirable. 

 The experimenter nould do well to consult IMr. Dalton's views 

 on the theorj' of Hygrometry, contained in his JShtenrolo'^icd 

 Essays, and in the Manchester Traruactiims, and to examine ti.e 

 investifjations of Professor Leslie, ( Helutitms of Heat und Mnistutc, 

 and Sirpplement to the Encyclojxedia Bfiiannica, Article IMr.TF.OR- 

 ology;) of Dr. Anderson {Edinburjih Encychpcsdia, Artide Hy- 

 grometer,) and of M. Gay-Lussac, (^Biot, Traits de Physiquf, 

 torn ii.) A good series of observations at high ten)pernturcs 

 will be found recorded in Nos. II. and III. of a Calcutta Journal, 

 entitled Gleanings in Science, 



VI. That experiments oji the Decrease of Temperature at in- 

 creasing hemhts in the Atmosphere be recommended as an im- 

 portant subject for the contributions of observers. 



Kote. Scries of observations for considerable periods of time on the 

 mean ifimperature of the air at fixed hours, and fit stations of 

 which the difference of height has been accurately n)ca.=;urcd, are 

 the most valuable. The best hours for observation aro those 

 which give most accurately the mean (ereiieratuvf of the period 

 of observation. The hourly observations at Leith Fort have de- 

 termined tiie hours which give the anuuil mean Icmperatuic 

 in this country to be about 9J a.m. and 8.^ p Ji. Experiiiicnlal 

 balloons have lately bicn imployed to assist th' solution of this 

 problem, v>hich is one of the mo-t ii.tcrcsting in Jleteor. Ic.gy ; 

 but the ir.vesiigati' n of it is neaily broiigiit to a stand for want 

 of suflicieiitly numerous observations. The obser\er may be re- 

 fened for infoimalion to Itumond, 3Ietnoircs sur la Formule Bu- 

 rotnetrique de la Mc'chniiqiic CJieste ; to the Ecscarches of Hum- 

 boldt ; to Professor Leslie, Supplement to the Encyclopadia Britav- 

 nica. Article Climate; to VvvMet, Elcjncns de Physique ; to Mr. 

 Atkinson's Paper on Refractions in (he itleinoirs of the Astronomi- 

 cal Society ; and to IMr. Ivory's Memoir on tlie same subject in 

 the Plulosoph'cal Transactions, and his Pa; ers in the Annuls <f 

 Philosophy. 



YU. That the observation of /he Temperature of Spriiigs at 

 different heights and depths should he pointed out as an object 

 of great interest, in prosecuting which insulated inquirers may 

 render essential aid to science. 



Note. When springs are copious, a few observations in the course of 

 the year suffice to give with great accur.icy their mean tem- 

 perature. The height of the springs above the mean level of the 

 sea, and the depth (if Artesian uells, should be carefully ob- 

 served; and where the coiresponding mean temperature of the air 

 can be obtained, it should be stated. In two points of view these 

 observations are important, independently of the inferences which 

 they may furnish as to the decrease cf heat in the atmosphere. 

 The great interest attached to the phaenomenon of the progressive 

 increase of temperature of the globe, as we descend through the 

 Strata, i-enders of value observations on the temperature of 

 springs at considerable heights, of springs in mines, and of those 

 brought to the surface from some depths by the process of boring. 

 Tiii» question has been treated with great success by M.Corpier, 



