undertaken at Petershirgh. I95 



paper ; that is to say, I bound together two surfaces at right 

 angles, fastened them with thread, and suspended it from 

 the car with a piece of packthread. This li^ht body showed 

 me, as will be hereafter mentioned, better than I could have 

 believed, all the variations in the direction of the balloon ; 

 on which account I shall call it the way-7viser. 



The balloon was filled with hydrogen gas in the Garden 

 of the first corps of Cadets, whence it ascended in the pre- 

 sence of a great many persons of distinction, the members 

 of the Academy of Sciences, and various men of science. 

 The decomposition of the water was effected by sulphuric 

 acid and iron filings, mostly from cast iron. The che- 

 mical apparatus consisted of twentv-five vessels, from each 

 of which a tin-plate tube was conveyed to a tub. For se- 

 parating the carbonic acid gas, mislaked lime was thrown 

 into water. Into each vessel were put three pood of iron 

 filings with fifteen pood of water, and three pood of sul- 

 phuric acid were pourtd over them. The balloon began to 

 be filled at eleven in the morning ; and, though the opera- 

 tion was completed at four in the afternoon, the experi- 

 ments to serve as a point of comparison with those made 

 in the higher regions of the atmosphere retarded our vovage 

 till a late period. The balloon contained 9000 cubic feet of 

 hydrogen gas. 



It weighed, with its whole apparatus 

 IVIr. Robertson and myself 

 The instruments and other apparatus for expe- 

 riments - - - - 

 Clothing - _ _ _ 

 Bottles with water and provisions 

 Ballast taken in - _ _ - 



Total of the weight 



The balloon, which in order to try its strength was first 

 filled with common air, was thirty English feet in diameter, 

 and perfectly round ; but in the air, as it was not entirely 

 filled with hydrogen gas, but sufficiently so for the voyage, 

 it appeared to be elongated. 



The wind was north-east, and favourable for our purpose; 

 but, that I might ascertain the direction of it more accu- 

 rately, we let oft' a small balloon before our departure at 

 about seven o'clock. At first it was driven by the north- 



* A pood is about forty pounds. 



N 2 can 



