Report of the Kew Committee, 



87 



presented the Observatory with a Standard — Baudin 7835 — which he 

 has compared very closely with his other standard instruments. 



The Committee has received very gratifying testimony as to the 

 accuracy of the Standard Thermometers constructed at the Obser- 

 vatory. In a paper contributed to the " American Journal of Science," 

 Dr. Leonard Waldo, of the Winchester Observatory, Yale College, 

 U.S.A., remarks that after a critical examination of three Kew 

 Standard Thermometers, in which every degree was separately mea- 

 sured, entailing no less than 2,300 micrometer readings, he came to 

 the conclusion that their errors are practically insensible and too 

 small to be detected with certainty. 



Professors Thorpe and Riicker have also been engaged in testing 

 very minutely three similar instruments made for them at Kew. Tn 

 a paper read at York before the British Association, Professor Riicker 

 stated " they had subjected the Kew Thermometers to the most 

 rigorous test possible, and they were able to announce that in one in- 

 strument the errors left, after the application of Welsh's method of 

 calibration and graduation, were not greater than four thousandths of 

 a degree Centigrade, and in no case did they much exceed one- 

 hundredth of a degree. As it is impossible to read on these thermo- 

 meters less than a hundredth of a degree with certainty, Welsh's 

 method as applied at Kew is almost perfect." 



VI. Aid to Observatories. 



Waxed Papers, Src, supplied. — Waxed paper has been supplied to the 

 following Observatories : — 



Aberdeen, Adelaide, Armagh, Bengal (Meteorological Department), 

 Colaba, Falmouth, Glasgow, Mauritius, Paris (Montsouris), Oxford 

 (Radcliife), Utrecht, Stony hurst, St. Petersburgh. 



Anemograph Sheets have been sent to the Mauritius Observatory, 

 and 



Blank Magnetic Observation Forms have been supplied to 

 Professor Remold, Royal Naval College ; 

 Professor Louis Perard, l'Universite de Liege ; 

 Professor Poynting, Mason's Science College, Birmingham ; 

 and to Mr. Casella. 



VII. Miscellaneous. - 



Loan Exhibition. — The instruments specified in the Report for 1876 

 still remain in charge of the Science and Art Department, South 

 Kensington, with the exception of the Invariable Pendulum Appa- 

 ratus recently withdrawn, as already stated, and the few articles 

 mentioned in previous reports. 



Fog Frevalence. — At the request of the Meteorological Council the 



