Report of the Kew Committee. 75 



November 21, 1887, January 23, April 11-12, May 21, August 3, and 

 October 19-22, 1888. 



The monthly observations with the absolute instruments have been 

 made as usual, and the results are given in the tables forming 

 Appendix I of this Report. 



The following is a summary of the number of magnetic observations 

 made during the year : 



Determinations of Horizontal Intensity 36 



,, Inclination 124 



Absolute Declination 39 



The magnetograph curves made use of in the preparation of the 

 tables of diurnal range of Declination (see Appendix I, Table III) have 

 been reproduced from the original photographs by means of an 

 eidograph kindly lent by Captain Wharton, F.R.S., the Hydro- 

 grapher. 



A complete set of self-recording, magnetographs by Casella, London, 

 similar in construction to the instruments recently supplied to the 

 Royal Cornwall Polytechnic Society, have been examined at the 

 Observatory. 



Information on matters relating to terrestrial magnetism and 

 various data have been supplied to Professors Riicker, Piazzi Smyth, 

 Dr. Rijckevorsel, and Messrs. Wilkinson and Harrison. 



Magnetic Reductions. At the request of the Rev. S. J. Perry, 

 copies of the Kew Horizontal Force curves for certain selected days 

 during the years 1883 to 1886 are now being made. 



II. METEOROLOGICAL OBSERVATIONS. 



The several self-recording instruments for the continuous registra- 

 tion respectively of Atmospheric Pressure, Temperature, and Humidity, 

 Wind (direction and velocity), Bright Sunshine, arid Rain, have been 

 maintained in regular operation throughout the year. 



The standard eye observations for the control of the automatic 

 records have been duly registered, together with the daily observa- 

 tions in connexion with the U.S. Signal Service synchronous system. 

 A summary of these observations is given in Appendix II. 



The tabulation of the meteorological traces has been regularly 

 carried on, and copies of these, as well as of the eye observations, 

 with notes of weather, cloud, and sunshine have been transmitted 

 to the Meteorological Office. 



Owing to trouble caused by bursting of the water-reservoir for the 

 thermograph wet- bulbs during frosty weather, and the risk of their 

 imperfect action owing to leakage of water, a double tank has been 

 made, so that in the event of the inner vessel bursting, the outer one 

 will prevent any loss of water. 



