March 4, 1886J 



NATURE 



423 



tion of unwinding will be loo + o'ii/ t, and the speed of 

 the balloon will be given by the formula — 



The preparations above referred to having been all 

 completed, on the first fine day thereafter, August 25, the 

 new mechanism was put on its trial, and behaved in a 

 manner leaving nothing to be desired. 



The balloon, which had been already filled for a certain 

 time, having lost a considerable portion of its ascending 

 force, M. Reuard was under the necessity, on this occa- 

 sion, of dispensing with the services of a third aeronaut, 

 and mounted in the company solely of his brother, Capt. 

 Paul Renard. The wind blew from the east. The speed 

 measured at a low height by means of small balloons, 

 appeared to be no more than 5 metres a second. Taking 

 as a basis the appro.ximate values of the preceding year, 

 they calculated on obtaining a proper speed of nearly 

 7 metres per second, and were greatly surprised at being 

 unable to gain the aerial current which prevailed at 250 

 metres above the valley of Chalais. The spiral, launched 

 at fifty-five rounds per minute, proceeded with perfect 

 regularity, yet they fell back — slowly, indeed, but con- 

 tinuall)'. Desiring, nevertheless, to continue the experi- 

 ment, and fearing to be carried away above the woods of 

 the Chaville quarter, M. Renard turned the head of the 

 balloon a little to the right, and soon, under the com- 

 bined action of the wind and its own speed, it took a 

 southern direction, and, the backward movement con- 

 tinuing, alighted after a voyage of 50 minutes close by 

 the farm of Villa Coublay, whither he had directed it. 



By reason of the bad weather the second definitive 

 experiment did not come off till September 22, when the 

 wind was blowing from the north-north-east — that is, 

 from Paris, and its velocity in the lower strata varied 

 from 3 to 350 metres per second. This time the aero- 

 nauts had their full complement of three : Capt. Renard 

 at the helm and the motory machine. Capt. Paul Renard 

 taking measurements and various observations, and, in 

 addition, M. Dutd-Poitevin. They started at 4.25 p.m. 

 in a moist and foggy atTiosphere. The spiral was set in 

 motion and the head directed towards Paris. Though at 

 first inclined to yaw, the course of the balloon soon 

 righted itself, and, crossing the railway line above the 

 station at 4. 5 5, the balloon reached the Seine towards the 

 western extremity of the island of Billancourt at 5 o'clock. 

 Here, a measurement being taken, the progress of the 

 balloon was found to be precisely 6 metres per second 

 (time of unwinding = 17", whence 



S = —-°-|- 0-117 = S"832 +0-117 = 5'999m ). 



At 5.12 p.m., after an excursion of 47 minutes, the balloon 

 entered the enceinte by the bastion 6;. It was only the 

 increasing damp and fog which induced the aeronauts to 

 cut short their voyage and make for home. The turning 

 of the balloon was easily effected, and, aided this time by 

 the aerial current, it approached its point of departure, 

 wh'ch was entirely concealed by the fog, with surprising 

 rapidity, retracing in 1 1 minutes the road it had taken 

 47 minutes to cover in going. The aerostat tacked 

 about at first to keep its head to the wind, and in 

 10 minutes the little skiff touched the sward, whence it 

 had ascended. During this voy.age the balloon mounted 

 to only 400 metres above the ground. 



The next day before Gen. Campenon, Minister of War, 

 and Gen. IJressonnet, President of the Committee of 

 Fortifications, the balloon, La France, performed a fresh 

 ascent with a success equal to that of the previous day. The 

 itinerary of this voyage was much the same as that of 

 the 22nd. The wind was weaker and bore the balloon to 

 Paris. The time of the passage was 17 minutes going, 

 20 returning. The landing was very easy, and the 

 balloon returned to the precise spot of its departure 



The voyage could not be further prolonged for lack of 

 ballast, the previous ascent having cost the balloon a 

 partial loss of its ascending force. 



On the valid basis of the experiments above described, 

 M. I-ienard lays down some fundamental formute for 

 calculating the resistance of balloons of construction 

 analogous to that of La France with network and car. 



Let R be the resistance in kilogrammes of the balloon 

 La France, moving by the point ; .S, its speed per second 

 in metres ; 6, the work of direct traction (motory work in 

 kilogrammetres) ; T, the work of the propelling screw 

 shaft (in kilogrammetres) ; T' , the work at the limits of 

 the motive power in kilogrammetres) ; then 

 ( R = 1-189 .S-. 

 ) e = i-iSgi--. 

 ^'' ) T - 2-30053. 

 ( r = 2-800 S^ 



At the rate of 10 metres, which would suffice for having 

 the direction in most cases, we get 

 J! = 1 18 -9 kilogrammes. 

 9 = 1 189 kilogrammetres. 

 T = 2300 kilogrammetres, or 31 horse-power. 

 7" = 2800 kilogrammetres. 



In general for a balloon of £> diameter (in metres) we 

 would get 



H = 0-01685 £>' S-. 

 e = 0-01685 D' SK 

 T = 0-0326 D" 6^ 

 T' = 0-0397 D"- S'^. 



It may be added that out of seven voyages, from 

 August 9, 1S84, to September 23, 1885, the aerostat has 

 in five returned to its point of departure. 



NOTES 



With much regret we announce the death of the eminent 

 Belgian botanist, Prof. C. J. E. Morren, of Liege, at the early 

 age of fifty-three years. 



At a meeting of the Managers of the Royal Institution, held 

 on Monday, March I, the Actonian Prize of one hundred 

 guineas was awarded to Prof. G. G. Stokes, P.R. S., for his 

 lectures on Light, in conformity with the Acton Endowment 

 Trust Deed. The following alteration has been made in the 

 lecture arrangements before Easter: — Prof. Dewar, F. R.S., 

 will begin a course of four lectures on Electro-Chemistry, on 

 March 25, in place of Prof. Tyndall, F.R.S., on Light. 



Dr. Julius von Haast, C.M.G., F.R.S., the eminent 

 geologist and Director of the Canterbury Museum, New 

 Zealand, who is charged as Commissioner with the exhibits from 

 that colony for the Colonial and Indian E.xhibition, has arrived 

 in London, and is busily at work in carrying out all the preli- 

 minary arrangements of the extensive court allotted to New 

 Zealand. Dr. von Haast has been exceedingly successful in his 

 journeys through the colony in obtaining large and valuable 

 collections illustrating the fauna, flora, and geology, as well as 

 collections of the art and industry of the Maori tribes. The 

 food and other fishes, the birds, the timbers, as well as other 

 native products and local industries will be well represented. 



M. Pasteur, at the last sitting of the Paris Academy of 

 Sciences, stated that out of 325 cases of inoculation for hydro- 

 phobia, only one had failed — namely, that of the youth Pelletier, 

 who came too long after being bitten, and under very unfavour- 

 able conditions. He advocated the establishment of an inter- 

 national hospital, to which patients would come from all parts 

 of the world ; and he suggested a discussion as to the locality 

 and the fund for its support. At the close of the meeting 

 Prof Pasteur announced that he should next investigate whether 

 diphtheria could not be treated by a similar process to that 

 which he had found so successful against hydrophobia. 



