205 Report of the Meteorological Committee. [Jan. 20 3 



Vapour-Tension. 



"Wind (Direction and Hourly Velocity). 



Eain (Hourly Amount). 



It may be asserted, without fear of contradiction, that no record of a 

 completeness and accuracy at all approaching that attained by the plates 

 in question has yet been attempted in any other country, and that more- 

 over the Meteorological Office is the only ^Meteorological establishment 

 which itself publishes the materials for testing the accuracy of its pub- 

 lished numerical values. 



In the matter of accuracy many important advances have been made 

 since 1867, owing to the growth of experience, and the methods of treat- 

 ment of the records have much improved. 



The text of the ' Quarterly Weather Eeport ' has been a consecutive 

 journal of the weather, and the tables have given the five-day means 

 of the barometer and the dry and wet thermometer, from hourly mea- 

 surements of the curves, together with monthly means of the same 

 elements, and of vapour-tension and deduced dry-air pressure, as well as 

 extreme readings of the barometer and dry thermometer. 



A request having been made for the publication of the actual hourly 

 readings of the measurements of the curves, this has been complied with. 

 These volumes have been issued since January 1874, and distributed to 

 the principal libraries at home and abroad. 



The preparation of the plates and tables above mentioned occupies 

 nearly the entire time of the available staff of the Office ; so that no pre- 

 sent prospect exists of a systematic discussion of the returns, so as to 

 calculate the periodical variations of the different elements. This for the 

 seven observatories will be a heavy task ; and it is for consideration 

 whether some special steps should not be taken for effecting it, as the 

 first five-yearly period over which the observations extended closed with 

 the past year, and it was held by the Vienna Congress that such calcula- 

 tions should be effected for " lustra " (periods of five years) ending with 

 years which, according to our present calendar, are multiples of five. 



The 'Quarterly "Weather Eeport' has contained in addition various ap- 

 pendices, which are as follows : — 



1869. Notes on easterly gales. 



1870. Mean barometrical pressure at telegraphic reporting stations. 

 Eainfall at telegraphic reporting stations. 



A translation of Bessel's Paper on the Determination of the 

 Law of a Periodical Phenomenon. 



1871. A discussion of the anemometrical results for Sand wick Manse, 



Orkney, 1863-68. 



Mean monthly rainfall at certain stations in the United King- 

 dom. 



Constants for Bessel's Formula for the Observatories for 

 1869-70. 



