526 SCIENTIFIC AND LITERARY NOTES. 



SCIENTIFIC BALLOON ASCENT. 



Several balloon ascents haye recently been made for scientific purposes by Mr. 

 Glaisher, accompanied by, and under the guidance of, the celebrated aeronaut Mr. 

 Coxweil. The most remarkable and one of the most eventful of these took place 

 on Friday, the 5th of September. The day -was capricious, beiag alternately fine 

 •and lowering, until finally, at the time of starting, an afternoon's rain seemed 

 inevitable. The cords were loosed exactly at one o'clock, and the balloon coasted 

 off in a southwesterly direction. The balloon, as on previous occasion, was not 

 quite filled, on account of the expanding effects of the atmosphere at two or three 

 miles' altitude. It contained 60,000 feet of excellent gas, prepared under the 

 able superintendence of Mr. Proud, engineer to the gas-works. Some pigeons 

 were on this occasion allowed to accompany the expedition. In addition to the 

 instruments previously taken, Mr. Glaisher took with him a camera, in order, if 

 possible, to take photographs of the different phases of the clouds. He also took 

 a newly-invented barometer, for the purpose of securing more correct observa- 

 tions of the state of the atmosphere than were previously possible. These obser- 

 vations have formally been taken by Gay-Lussac's siphon barometer and an 

 aneroid ; but as the correctness of the readings of the siphon barometer mainly 

 depend upon having a perfectly calibred tube, and as the large size of the general 

 barometer tube renders perfect calibration impossible, or at least very difficult, 

 Messrs. Negretti and Zambra have constructed a barometer expressly for the pur- 

 pose of checking the observations which have been made in order to test their 

 correctness. With this view a good tube was selected, six feet in length, and 

 "the mercury boiled through the whole of that length. A cistern was then blown 

 on its lower extremity, and a stopcock added, by which means the mercury was 

 allowed to decrease inch by inch from the tube into the cistern, and the rise 

 which took place in the cistern was subsequently accounted for in dividing the 

 scale ; the upper part of the tube was used to construct the barometer ; and by this 

 instrument a direct reading is obtained without any corrections being necessary 

 for the displacement of the mercury in the cistern down to eight inches. The 

 difference, if any be found, between this barometer and the Gay-Lussac siphon 

 used in former ascents will be due to the inequalities in the tube of the latter. 

 Among others, Lord Wrottesley was present when the ascent took place. The 

 following interesting account of this ascent was furnished by Mr. Glaisher to 



the ' Tknes ' :— 



To the Editor of the ' Times: 



Sir, — On the earth at Ih. 3m. the temperature of the air was 59° ; at Ih. 13ra., 

 at the height of a mile, it was 39" ; and shortly afterwards we entered a cloud, 

 which was about 1100 feet in thickness, in which the temperature of the air fell 

 to 36i°, and the wet-bulb thermometer read the same, showing the air here was 

 saturated with moisture. On emerging from the cloud at Ih. I7m. we came into 

 a flood of light, with a beautiful blue sky without a cloud above us, and a mag- 

 ificent sea of cloud below ; its surface being varied with endless hills, hillocks 

 mountain chains, and many snow-white masses rising from it. I here tried to 

 lake a view with the camera, but we were rising too rapidly and revolving too 

 Tapidly for me to do so ; the flood of light, however, was so great that all I should 

 have needed would have been a momentary exposure, as Dr. Hill Norris had 

 kindly furnished me with extremely sensitive dry plates for the purpose. 



