312 Mr. G. J. Symons. [June 21, 



amount of the reduction was unknown, and, owing to the absence of 

 hourly readings at night, no data existed for determining the shape 

 of the curve during the night and early morning hours. 



The Council of the Meteorological Society have therefore thought 

 it expedient to endeavour to obtain accurate and complete information 

 upon the subject. The author had been for some years in communi- 

 cation with Mr. E. C. Hackford, verger of the parish church of 

 Boston, Lincolnshire, the tower of which rises, quite free from any 

 obstructions, in a very flat country, to the considerable height of 

 273 feet. The site was extremely suitable, and Mr. Hackford was a 

 practised observer ; he having consented to make the observations, 

 arrangements were made for obtaining instruments. The first 

 essential was a thermometer which could be read without climbing to 

 the top of the tower. This requirement having been brought to the 

 knowledge of Sir W. Siemens, F.R.S., he very kindly placed at the 

 disposal of the Council one of his electrical thermometers. 



The principle of these instruments was fully explained by Sir W. 

 Siemens in the Bakerian Lecture, 1871, and published in a paper " On 

 the Dependence of Electrical Resistance to Temperature," printed in 

 vol. iii of the " Journal of the Society of Telegraph Engineers." It 

 is therefore merely necessary to state that the thermometer consists of 

 a spiral of insulated wire coiled round a core of wood, the whole being 

 protected by a brass sheath. The resistance of the wire increasing 

 with increase of temperature it is only necessary to measure the 

 resistance in order to learn the temperature. The current is provided 

 by a six-cell Leclanche battery, and a light cable carries the insulated 

 wires up to the thermometer, and connects it with a galvanometer 

 with a roller contact. The position of the contact maker when the 

 galvanometer is at zero depends upon the resistance in the thermo- 

 meter, and therefore the position of the contact maker, as shown on a 

 graduated scale, gives the temperature. 



On receipt of the thermometer from Messrs. Siemens Brothers' 

 works, it was at once forwarded to Kew Observatory for verification, 

 and the report was that it worked very satisfactorily, but was 

 somewhat sluggish. 



The consent of the vicar (Canon Blenkin) to the use of the tower of 

 the church having been obtained, the Assistant Secretary of the 

 Meteorological Society (Mr. W. Marriott) was intrusted with all the 

 arrangements. He went to Boston at the end of February, 1882, and 

 erected the following instruments. 



(1.) In the churchyard, where there is a good exposure, a 

 Stevenson screen containing dry bulb, wet bulb, maximum and 

 minimum thermometers, all at 4 feet above the ground. 



(2.) On the roof of the belfry, in its south-east corner, 4 feet above 

 the roof, and 170 feet above the ground, a precisely similar Stevenson 



