160 Mr. Howard's Meteorological Journal, [Feb. 1824. 



Note— Some doubt having arisen as to the accuracy of the high main lately assigned 

 to the barometrical observations in this Register, we have thought it needful to verify the 

 actual height of the barometer employed, by comparison with a good standard. 



On the 1 6th inst. at three, p. m. I suspended by the side of the barometer in question, 

 the one belonging to my friend J. F. Daniell, described in page 338 of his " Meteoro- 

 logical Essays," and which he considers (with due allowance for the depression of the 

 column, caused by the smaller diameter of the tube) to agree with the excellent standard 

 barometer, lately constructed under his direction for the Royal Society. The result was 

 very satisfactory : the mountain barometer, and that employed for this Register, stood 

 respectively at 30-66 in. ; nor could a difference of 1-1 00th of an inch be found between 

 them, by either of two observers, who examined them at intervals during a full hour. 

 The temperature of each was 55° : the inner diameter of the mountain barometer (the 

 quicksilver of which has been boiled in the tube), is - 1 5 in. : the inner diameter of the 

 wheel barometer, as nearly as could be ascertained, 0-23 in. The quicksilver has not 

 been boiled in this instrument. The barometer was very nearly stationary on the 16th, 

 from noon to midnight. ' 



In a comparison made this day, for an hour before noon, in the lower part of the scale, 

 the instruments at the conclusion stood thus, at temp. 58°. 



The siphon barometer '28*94 



The mountain ditto 28'895 



Difference -045 



The correction for the capacity of the cistern in the mountain barometer being applied 

 reduces the difference in the present case to -014, and creates a difference in the former 

 of - 01 1 in. both in excess on the part of the siphon barometer. The corrections for tem- 

 perature and capillary depression cannot here be so accurately applied, on account of the 

 different construction of the two instalments. On the whole, there appears no ground 

 to disturb the adjustment of our own barometer. 



Tottenham, FlMt'Mmth, 23, 1824. L. HOWARD. 



