1865.] Physical Science. 735 



expended in dispelling cirri cloud and vapour before it reached the 

 earth's surface. The heat of the moon at the last quarter, or a day or 

 two after entering that phase, seemed to be greater certainly than 

 when at the full. 



On Monday, the 11th September, the proceedings in Section A 

 commenced with the Eeport of the Balloon Committee, read by 

 Mr. Glaisher. It stated that the committee had been re-appointed 

 last year, in order, 1st, to examine the electrical condition of the air 

 at different heights ; 2nd, to verify the law of the decrease of tempe- 

 rature, as found from summer-day observations already made, with 

 day observations at other seasons of the year, but principally in the 

 winter and adjacent months ; 3rd, magnetical experiments ; observa- 

 tions with the spectroscope, the currents of the atmosphere, solar 

 radiation at different heights, and hygrometrical observations, though 

 secondary, were to be held as very important subjects of investiga- 

 tion ; 4th, to arrange for observations at night, and to make such 

 observations if possible. With respect to the first subject, no farther 

 progress had been made, the instrument prepared for the purpose not 

 having been rendered available for use. Under the second and third 

 heads some progress had been made, though not to the extent anti- 

 cipated. As to the fourth object, no night observations had actually 

 been made. To take such observations it was imperatively necessary 

 to have some means of illiunination, so that the instruments could be 

 read. Various suggestions had been made on this point, but the best 

 plan seemed to be to employ a Davy lamp. Two such lamps had 

 been made of copper, for Mr. Glaisher, so that the proximity of 

 magnets did not affect them. Experiments had shown that these 

 lamps might be used with perfect safety, and that they kept well 

 alight, besides affording a source of grateful warmth not before 

 possessed. All necessary arrangements were now made for night 

 observations, and a series of such observations would be very useful, 

 though there were no results yet for presentation. The same instru- 

 ments, with the addition of a fine spectroscope and a delicately- 

 mounted magnet, had been employed, as during the previous year. 

 The instruments were attached to the outside of the car, and were 

 easily read in that position. Up to the last meeting of the Associa- 

 tion twenty-two ascents had been made, of which seventeen had taken 

 place in June, July, August, and September, and five only in the 

 other months of the year, viz. one in January, one in March, two in 

 April, and one in October. Of the summer ascents, one had been 

 made in the morning, and the rest in the afternoon or evening. The 

 committee considering that day and night experiments in summer 

 had better be brought together before more were made, Mr. Glaisher 

 devoted all his efforts to secure as many ascents as possible between 

 October and April, but he had succeeded in three instances only, on 

 December 1st and 30th, 1864, and on February 27th last. The three 

 ascents were made from Woolwich, and the paths of the balloon were 

 shown in diagrams. The small number of ascents was due to winter 

 being an unfavourable season for balloon experiments. But as with 

 regard to the progressive diminution of temperature with elevation, 



