1821.] Mr. BlackwaWs Thermometrical Observations. 



297 



Article VIII. 



A Series of Observations on the Thermometer, made on June 15, 

 1821, at Crumpsall, in Lancashire, for the Purpose of ascer- 

 taining the most convenient Method of obtaining the Mean 

 Temperature of the Natural Day. By Mr. John Blackwall. 



(To the Editor of the Annals of Philosophy.) 



SIR Crumpsall, July 20, 1821. 



Should you consider the following observations and remarks 

 at all calculated to interest your meteorological readers, they 

 are much at your service. Your obedient servant, 



John Black wall. 



It has long been a subject of regret among meteorologists, that 

 a greater degree of uniformity is not observed in the time and 

 manner of taking their observations ; the irregularity which pre- 

 vails rendering a comparison of registers kept by different 

 persons almost impracticable, and nearly useless. 



It is hardly to be expected, however, that observers will be 

 induced to adopt a more regular system, or that they will be 

 i»fluenced any otherwise than by convenience, or caprice, until 

 the best mode of conducting meteorological observations has 

 been found by direct experiment. 



In order to attempt the attainment of this object, as far as 

 regards temperature, on the evening of June 14, a common mer- 

 curial thermometer, a Six's thermometer, and a pair of horizontal 

 self-registering thermometers, arranged according to Rutherford's 

 method, were placed in the open air, out of the direct influence 



