66 



Mr. R. H. Scott. 



and the Royal Observatory at Greenwich ; but the proposal failed of 

 success. 



The experiments were continued until the end of May, 1874, when 

 the apparatus employed, with the exception of the Russian pendulums 

 and their accessories, was, at the request of the Secretary of the Royal 

 Society, received at Kew for storage. 



1874. The Magnetograph instruments were dismounted in January, 

 1874, for the purpose of thorough examination and readjustment. The 

 necessity for this measure is obvious, when it is remembered that the 

 instruments had been in unintermitted action for the period of fifteen 

 years. 



The scale- values were accordingly redetermined, and the instruments 

 handed over to Mr. Adie for examination and repair. They were 

 returned and remounted in May, but were not at that time set in 

 continuous action, inasmuch as it was intended that the automatic 

 records should be suspended for the entire year, so as to commence 

 a new series of observations with the year 1875. 



In this year an improved automatic Electrograph, invented by Sir 

 W. Thomson, was erected and set in operation. 



In the year 1873 a grant had been obtained from the Grovernment- 

 Grant Committee for the purpose of carrying on a series of experiments 

 on the constants of Robinson's Anemometers ; and a piece of ground 

 in the Park was rented. Several anemometers, of various construc- 

 tions, were erected therein. 



The experience of a few months was sufficient to show that the ex- 

 posure in the Park was not nearly sufficiently open to afford facilities 

 for testing the instruments at any but very low velocities, and not 

 satisfactorily even in such cases. Application was therefore made to 

 the Secretary of the Crystal Palace Company for permission to employ 

 a rotary machine driven by steam-power, so as to be able to vary the 

 velocities at pleasure. 



Consent having been most freely given, the experiments were com- 

 menced, and the instruments tested at various velocities up to about 

 thirty miles an hour, the highest attainable by the apparatus. 



A paper on the results of these experiments was laid before the 

 Royal Society by Prof. Stokes in 1881 (Proceedings Royal Society, 

 Yol. XXXII, p. 170). 



1875. The year was marked by the recommencement of regular 

 work with the Magnetographs. The instruments were set in action on 

 the 1st of January, 1875, and therewith the second series of continuous 

 photographic records of magnetic phenomena was inaugurated. 



The principal constants employed in the computations for the Tables 

 used in the reduction of the monthly absolute observations which had 

 been determined by Mr. Welsh were also re-examined. A memorandum 

 containing the results of the observations in question for the twelve 



