318 



Report of the Kew Committee. 



take frequent pictures for the purpose of determining the rate of 

 motion of clouds. Accordingly the telegraph cable uniting the two 

 stations was buried in the ground (permission having previously been 

 granted by the lessee of the Old Deer Park), and the stands and 

 electrical fittings were made fixtures. 



A quantity of photographic plates, prepared in accordance with 

 Captain Abney's formula, were also obtained from a manufacturer, 

 and certain arrangements made in the photographic laboratory of the 

 Observatory for their convenient manipulation. Blank forms for 

 the computation of the cloud positions and motions were also drawn 

 up and printed. 



Between July 6th, when the installation of the apparatus was com- 

 pleted, and the date, when the experiments were brought to a close, 

 in accordance with the instructions of the Meteorological Council, 

 168 cloud negatives were obtained on 23 days, from these 62 approxi- 

 mate determinations of the rate and direction of motion of clouds 

 at heights varying from 3,000 feet to 50,000 feet have been secured. 



A detailed report of the work is being drawn up for presentation 

 to the Meteorological Council. 



Solar Radiation Thermometers. — The Committee have made a 

 great number of experiments on the construction and exhaustion of 

 the solar radiation thermometers, and the Superintendent is engaged 

 on a report to be communicated to the Royal Society. The general 

 result would indicate that solar radiation as measured by the black 

 bulb thermometer in vacuo has hitherto been considerably under- 

 rated. 



Baily's Wind Integrator. — This instrument, after working success- 

 fully with electrical counters for some time, was simplified by the 

 inventor by the substitution of mechanical counters. These being 

 found to work satisfactorily, Mr. Baily removed the instrument in 

 May for the purpose of exhibiting it at the International Inventions 

 Exhibition. 



The spare Beckley Anemograph to which it was attached has been 

 dismounted, and together with the de la Rue recorder (see report for 

 1879) has, by direction of the Meteorological Council, been forwarded 

 to Mr. Munro to be reconstructed as a Beckley recorder of the 

 original type. 



Electrical Anemograph. — The Meteorological Council having granted 

 a sum of money for experiment, and placed at the disposal of 

 Mr. W. Preece, F.R.S., Superintendent of Telegraphs, an old 

 Beckley Anemograph of the 1858 model, that gentleman had it 

 fitted up by Mr. Kempe, of the Chief Engineer's Department, 

 G.P.O., so as to record electrically, and it was erected on the Experi- 

 mental House of the Observatory. The velocity attachment has 

 woiked most satisfactorily for the past six months, neither batteries 



