TRANSACTIONS OP THE SECTIONS. 569 



On a peculiar Oscillation of the Barometer. By the Rev. 

 J. Hailstone. 



The author presented a table of observations on the height of 

 the barometer, at short intervals of time, between November 28, 

 1833, and January 10, 1834. The circumstance in these ob- 

 servations, which the author especially desires to point out for 

 the attention of meteorologists, is, a small and short oscillation 

 of the mercury, sending it up seldom above a few thousandths 

 of an inch, after which deviation it resumes its usual march 

 again. 



On the use of Leslie's Hygrometer with a new Scale. By 

 H. H. Watson. 



In this communication, the author states the reasoning and 

 experiments by which he was induced to apply to Leslie's 

 hygrometer a scale of equal parts, such that the cold produced 

 by evaporation of water, being measured upon this scale, and 

 the parts considered to represent degrees of Fahrenheit's ther- 

 mometer, the dew-point, or constituent temperature of the 

 vapour, should be immediately known. The author states, as 

 the consistent result of many experiments, that the difference 

 in degrees between the temperature of the air and the dew- 

 point, is to the degrees of cold produced in Leslie's hygrometer, 

 by evaporation of water, as 20 to 13: this ratio is consequently 

 employed for the divisions of the new scale of the hygrometer, 

 which thus is supposed to give results sufficiently in accordance 

 with the direct experiment on the dew-point, to justify its use 

 in cases where rigorous accuracy is not demanded. 



Account of Experiments on the Expansion of Stone by the ap- 

 plication of Heat. By Alexander J, Adie, Civil Engineer. 



The author laid this communication before the Association 

 principally to give the expansion of sandstone, taken from what 

 is called the Liver Rock of Craigleith Quarry. The subject 

 under experiment with the pyrometer, is placed in the interior 

 of a double metaUic case, which is heated by means of a current 

 of steam, a method which is very convenient for keeping up a 

 steady temperature for any length of time, and affords great 

 facility in preserving the substance in the same hygrometric 



