1876.] Report of the Meteorological Committee. 205 



sanction the insertion on the estimates of the full sum proposed by the 

 Meteorological Committee for the year 1867-68 ; and accordingly the Com- 

 mittee at first determined to defer the establishment of the station at 

 Aberdeen, in consideration of the greater importance of records from 

 Valencia. At the request of the authorities at Aberdeen, conveyed 

 through the Duke of Richmond, Chancellor of that University, the Com- 

 mittee resolved to reconsider their proposal ; and ultimately Aberdeen 

 was included in the list of places fitted out with self-recording instru- 

 ments. 



The choice of these stations was guided by the fact of the existence in 

 each locality, except Valencia, of some scientific body to whom the instru- 

 ments could be entrusted. This involved the necessity of placing the 

 instruments in the best available positions on the premises of the respec- 

 tive institutions, the funds available being totally inadequate for the 

 erection of special structures for the reception of the instruments or the 

 maintenance of special observing establishments. Hence have arisen the 

 defects in arrangements as concerns temperature in regard of elevation 

 above the ground at Falmouth and Aberdeen, and to a less degree at 

 Valencia, and as to proximity to buildings in all the observatories. In 

 respect of the four other observatories, not above named, there is no 

 doubt the thermometries! indications do afford as thoroughly satisfactory 

 a record of temperature as is required — this point having been proved by 

 direct experiments by Dr. Stewart for Kew, and by the Rev. Dr. Robin- 

 son for Armagh. 



Absolute uniformity in conditions of exposure is totally unattainable, 

 as was fully recognized at the Vienna Meteorological Congress in 1873. 



The observatories were set in action in 1868, and with the year 1869 

 the publication of the ' Quarterly "Weather Report' was commenced. This 

 was projected in order to overcome the difficulty, universally recognized, 

 of the absence of uniformity in epochs of observation in the different 

 countries. A reproduction of the automatic curves was considered to be 

 of paramount importance in order that the records at observatories should 

 be independent of any choice of hours for observation or of any scales, 

 and the value of such a reproduction was strongly urged by the Com- 

 mittee of Inquiry (1866). 



The execution of the plates was rendered possible by the invention of 

 certain special instruments and processes, for which the Office is indebted 

 to Mr. F. Gralton and Mr. De La Rue, and which are in constant use, as 

 explained in the several Annual Reports of the Office. 



The curves were at first reproduced by the lithographic process, but 

 of late years that of copper-plate printing has been introduced. 



The degree of accuracy aimed at is 0*02 in. for the barometer, and 

 o, 5 for the thermometer; and the plates furnish a continous record of — 

 Pressure. 

 Temperature (Dry and Wet Bulb). 



