HISTORY of the SOCIETT. 



17 



Phy/. CI. Dr Monro read a paper, concerning the Commu- 

 nication of the Ventricles of the Brain with one another, in 

 Man and Quadrupeds. This paper is pubhfhed in Dr Monro's 

 book, entitled. Three Treatifes, &c. 



1794. 

 Aug. 18. 



Dr Monro on 

 the romn-uaica- 

 tion of the ven- 

 tricles of the 

 brain. 



Mr Keith alfo communicated an Improvement of the Mer- 

 curial Level, defcribed in the Second Volume of the Tranfadlions 

 of the Society. 



This improvement confifts in a contrivance for avoiding the 

 trouble of pouring the mercury out and into the level, every 

 time it is ufed. Belide the canal of communication at the bot- 

 tom, between the two upright columns of mercury, on which 

 the flats fwim, (fee Vol. II. Part II. No. III.), there is, in the 

 new conflrudlion of the inftrument, another canal, parallel to 

 the former, cut in the tipper part of the wood, which allows 

 the air to circulate freely, according as the mercury below rifes 

 or falls. The whole is made perfe(5lly clofe, fo that no air can 

 get admittance. 



The inftrument may be carried about in this manner, with 

 the mercury remaining in it ; and though by agitation that 

 fluid calcines, and is converted into a grey powder, this only 

 happens when it has free accefs to vital air ; and as all fuch ac- 

 cefs is here prevented, the mercury will not lofe its metallic 

 luftre. 1 



The level, in this form of it, as it requires no previous ad- 

 juftment, is very commodious, and, when much accuracy is not 

 required, may be ufed with advantage. 



Mr Keith on m 

 improvement of 

 the raercurial 

 • level. 



Phyf. CI. Dr Anderson read a paper, entitled, Obfervations 

 on Wool-bearing Animals. 



Phyf. CI. Mr Playfair communicated an Abftradt of a 



Journal of the Weather, kept at his Houfe in Windmill Street, 



Vol. IV. c for 



1 79 J. 



Jan. 5. 



Dr Anderlon 

 on wool-bear- 

 ing animals. 



Feb. 2. 

 Mr Playfair on- 

 the weather of 

 J 794' 



