146 report — 1865. 



To take observations in the air at night, it is imperatively necessary to 

 have some power of illumination, so that the instruments can be read. 



Very many suggestions have been made for the benefit of the occupants 

 of the car ; among them phosphorus and the use of glow-worms have been 

 mentioned. The latter I feared would lose their luminosity at a low tem- 

 perature. The best of all seemed, however, to be a well-made miners' Davy- 

 lamp ; and through the kindness of my friends T. Sopwith, Esq., F.R.S., and 

 E. Potter, Esq., of Tynemouth, two have been most carefully made by Mr. 

 H. "Watson, of Newcastle, of copper ; so that their presence near to magnets 

 is innocuous. 



These lamps, with their lights burning, have been placed in a volume of 

 gas, completely surrounded by it, without any bad effect following the im- ' 

 mersion ; and what is more important, I have had one of these lamps burning 

 during an ascent made on the 27th of February of this year, coming down 

 alight — the only difference between with and without the light being that 

 in the latter case I had a source of heat to wann my cold fingers, which I 

 never had before. 



I corsider tliat at present all necessary arrangements have been made for 

 night observations, so far as light is concerned ; and I cannot but regard this 

 as an advance, although I have not any results to present of observations made 

 at night, and we therefore are still in utter ignorance, without a single obser- 

 vation of the processes in operation at night to guide us, at any distance from 

 the earth. Such a series of observations, even though only to the height of 

 half a mile, would be veiy valuable indeed. 



§ 1. Instruments and Apparatus. 



The instruments used were for the most part the same in construction as 

 those in the preceding year; in addition, however, to them, there was a 

 very fine spectroscope by Mr. Browning, and a delicately mounted magnet 

 lent by Capt. Evans, F.K.S. 



§ 2. Observing- Arrangements. 



The instruments were in all cases placed on suitable framework attached 

 to the outside of the car, and were in this position easily read by myself 

 standing at the end of the car. 



Circumstances of the Ascents, and General Observations. 



Up to the last Meeting of the Association there had been 22 ascents, of 

 which 17 had been made in the months of June, July, August, and Septembe", 

 and 5 only in the other months of the year, viz. 1 in January, 1 in March, 

 2 in April, and 1 in October. Of those made in the summer months, one only 

 had been made in the morning, and 16 had been made in the afternoon or 

 evening, with a declining sun. 



Efforts were therefore directed to day experiments between the months of 

 October and April, it being considered that the day and high experiments in 

 summer already collected had better be brought together and discussed before 

 any more of such experiments were made, and that in future attention should 

 be directed to those points of research needing further elucidation. 



I therefore devoted all my leisure between the months of October and April 

 to securing as many ascents as I could between these times, and regret to 



