46S 



Barometrk Ohervations. 



The barometer is an excellent portable one, and with the at- 

 tached thermometer hangs on the landing place of a first flight of 

 stairs, with the surface of the mercury in the basin 12 feet from 

 the ground, in a free circulation of the air, and where neither 

 is affected by any artificial heat. 



Yours most respectfully, 

 Mr. Tilloch. ' Thos. Squire. 



To Mr. Tilloch. 



Leighton, Dec. 18, 1820. 

 Dear Sir, — I send you the barometrical observations made at 

 this place, on Monday the llth inst., from a standard baro- 

 meter made by the late Mr. Ramsden. 



8'> 

 9 



10 



11 



12 



Wind. 



W.S.W. 



w. 



I have been also favoured with the observations of Col. Beaufov, 

 at Bushy Heath, as below : 



9 



10 



11 



12 



There is not that regular conformity in the motion of the two 

 instruments that might have been expected, but this apparent 

 anomaly ought to render us more dilisjent in search of the cause. 

 I do not know how far the equal pressure of the atmosphere has 

 been proved to extend ; but if gentlemen will be careful to note 

 the height of their barometers at the conmicncement of each 

 hour from S to 12 on the secoiid Alonday of January 1S20 and 

 following months, and communicate the result to the public 

 through your Magazine, it will enable u.s to know how far former 

 observations of this nature ought to be relied upon for accuracy, 

 and m.ay lead us to discover the necessary corrections to be ap- 

 plied to past and future observations. 



There may be some trifling difference in the height of the scale, 

 upon instruments made by different artists ; but it will he easy to 

 find the error of the scale by a comparison with a good standard 

 instrument y and it would be well if instrument-makers were to 

 take the trouble of ascertaining and marking the errors of the 

 scale upon the instrument before it was sold. 



I have 



