LIBRARY 

 NEW YO*K 

 IMITANICAI 



Reprinted from SciF.fcfcfV pages 26-28, Vol. LVII, 

 No. 1462, January 5, 1923. 



THE MUSCH RAIN-CORRECTING MOUNTING 

 FOR POROUS PORCELAIN ATMOMETERSi 

 Two years ago Livingston and Thone 2 de- 

 scribed "A simplified non-absorbing mounting 

 for porous porcelain atmometers" which, by 

 reason of its simplicity of construction and 

 operation as well as its inexpensiveness, has 

 since come into very general use. The essential 

 feature of this mounting is a short column of 

 mercury placed near the upper end of the 

 straight glass feed-tube which connects the 

 atmometer above with 'the water reservoir 

 below. This column of mercury, held in place 

 by two plugs of glass wool (one above and the 

 other below), acts very effectively as a valve to 

 prevent the passage of water from the atmo- 

 meter down the tube into the reservoir, at the 

 same time having no effect whatever on the 

 passage of water up the tube to replace that 

 lost by evaporation. 



Notwithstanding the obvious advantages of 

 the Livingston-Thone mounting, there are cer- 

 tain objectionable features attendant upon its 

 use which can not be overlooked. To begin 

 with, the mercury valve with its glass wool 

 plugs has to be properly constructed every 

 time it is needed for use : once a season at any 

 rate. Again, in sucking water through the 

 tube, during the setting up of the apparatus, 

 there is clanger of drawing slivers of glass wool 

 into the mouth. But perhaps the most serious 

 objection has to do with the accumulation of 



o-J i Contribution from the Osborn Botanical Lab- 



CD 



■< — oratory. 



_, ^ Science, N. S., 52: 85-87, 1920. 



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