oftheMandofBarbadoes. 61 



tending from 1 p.m. backwards to the hour of minimum, and from 1 p.m. 

 to the point of mean temperature in the evening, and that extending 

 from the hour of minimum backwards to the same point, are closely re- 

 presented by the corresponding parabolic arcs ; and it is highly probable, 

 that, had these observations been continued for twelve months, the 

 agreement would have been still closer. 



The mean of the 18 hourly observations for the three months is 

 81°.2ir), which is an excess of the actual mean temperature of the period, 

 80''.364, by 0".8o2. Subtracting this quantity from the mean of the 

 observations for each month, the result must be very nearly the mean 

 temperature of the corresponding month. By this process, 80°.442, 

 80''.021, and 80°.629, are obtained as the mean temperatures of June, 

 July, and August respectively. The mean of these observations at 9 

 A.M., 3 P.M., and 9 p.m., for the three months, is in excess of the mean 

 temperature of the period by 1MG6 ; and, if the mean of the observa- 

 tions at these hours, for each, be reduced by this quantity, 80^.404, 

 80°.054, and 80".627, are obtained as the mean temperatures for the re- 

 spective months — temperatures differing so little from those obtained 

 from 18 hourly observations, that, for all practical purposes, they may 

 be safely substituted. 



The observations, of which Table IT. is an abstract, v/ere commenced 

 on the 11th May 1841, and were continued till the beginning of Feb- 

 ruary 1842. Subsequently to October, I was unable to make the 

 observations exactly at the hour ; but the deviations having been noted, 

 a correction for the mean amount, derived from the hourly observations 

 in June, &c., has been applied to the results in the table. The mean de- 

 viation in a month nowhere exceeded ten minutes, and no single obser- 

 vation was made more than thirty minutes from the corresponding hour. 

 Notwithstanding the latitude thus taken, the observations at 3 p.m. and 

 9 p.m., in the last two months, were frequently omitted, from unavoid- 

 able circumstances; but, as in neither case did the omission exceed one- 

 third of the whole number that ought to have been made at 9 p.m., nor 

 one fourth of those that ought to have been made at 3 p.m., the means 

 given in the table, when the great regularity of the atmospheric pheno- 

 mena in that climate is considered, will be found not undeserving of 

 confidence. From October onwards, the minimum is probably about 

 0".2 Fah. too high. 



The dew point was calculated by ])r Apjohn's Tables, from the indi- 

 cations of a wet bulb thermometer. The table of elasticity of vapour 

 employed was that given in the appendix to the report of the Committee 

 of the Royal Society on Physics and Meteorolog}-. In the reduction 

 the height of the barometer was uniformly assumed to be 30 inches. 



