1813.] 



Sclent'ific Intelligence. 



467 



of 44*6 of an unknown inflammable gas^ and 55 "4 of oxygen 

 gas. 



III. Fure Alumina, 



Mr. Webster lately picked up a very curious mineral upon the 

 beach between Brighthelmstone and Beachy Head. It is a white 

 substance, similar in appearance to a mass of tobacco-pipe-clay; 

 hut when examined by Dr. WoUastoo was found to consist of 

 nothing else than pure alumina. It must have fallen down from 

 the cliff ; but its repository was not discovered. It would be well 

 worthy the attention of those Gentlemen who live near the spot 

 to endeavour to find out the position of a bed which would be so 

 interesting in many points of view. 



IV. Atmomeier, 



Professor Leslie, of Edinburgh, to whom the scientific world 

 lies under such obligations for his important discoveries on heat, 

 and his differential thermometer, which enables i3s to detect the 

 changes in temperature that take place in any particular point of 

 space, independent of the general changes which are going ou 

 in the place where the observations are made, has lately con- 

 trived an instrum.ent for measuring the rate of evaporation^ 

 which promises to be of essential service to meteorology, and 

 ought to make one of the instruments of every meteorologist, and 

 to be carefully attended to in every part of the world. Combined 

 v/ith a knowledge of the temperature where the instrument is 

 used, it would furnish us with the means of ascertaining the 

 quantity of vapour that exists in the atmosphere, and thus 

 answer the purpose of a hijgronieter as well as atmGmeter, 



A representation of Mr. Leslie's atmoweter is 

 given in the margin, and we shall here add such 

 a description of it as will put it in the power of 

 any competent workman to construct it at pleasure. 

 It consists of a thin ball of porous earthen ware, 

 two or three in^'.'hes in diameter, to which is 

 firmly cemented a long and rather wide tube, 

 bearing divisions, each of them corresponding to a 

 quantity of water which would cover the outer 

 surface of the ball to the thickness of yo^'oir^h of 

 an inch. These divisions are numbered down- 

 wards, to the extent of 100 or 200, according 

 to the length of the tube. To the top of the 

 tube is fitted a brass cap, having a collar of 

 leather, which, after the cavity has been filled" 

 with distilled or boiled water, is screwed tig The outside 

 of the ball being now wiped dry, tlie instrument is sus- 

 pended out of doorsj and exposed to the free «ction of the air. 



1 



