190 



SCIENCE. 



[VOT.. II., No. 28. 



Suddenly, without any shock, the basket seemed 

 to drop from under their feet. A moment later they 

 were violently thrown down by the sudden stopping 

 of their fall. It was twenty-seven minutes past four. 

 The ascension had lasted eleven minutes, and two 

 minutes were occupied by the fall of seven hundred 

 and three metres. 



They found themselves suspended about two me- 

 tres from the pavement in the courtyard of a house 



in Saint-Ouen, the ropes and materia! of the balloon 

 havhig caught on the roof. The yard was not more 

 than four metres long by three wide. To complete 

 their good luck, there was a flight of steps which 

 gave them an easy means of reaching the ground. 



Mr. Jacque was in his studio, and saw the balloon 

 in the air. Seeing that somethii\g unusual was hap- 

 pening, he seized a pencil, and hastily drew the suc- 

 cessive forms which are reproduced in figs. 1 to 4. 



As to the drawings, he says, " I could only indicate 

 very imperfectly the ropes and basket, which I could 

 hardly see. It is necessary to remark, that the phases 

 represented ought to be supposed as following closely 

 one another, and constantly clianging. I suppose 

 that the time during which the fall was visible to me 

 was about one minute, and the distance fallen five 

 hundred metres. At the moment when I saw the bal- 

 loon taking the last form (fig. 4), it was descending 

 more rapidly, and disappeared behind 

 the left slope of JMoiitmartre. It did 

 not seem more than one kilometre 

 distant from me; but in this I was 

 mistaken." 



Tlie sketches (fig. 6) of the fall as 

 seen by M. L. Gillon are not accom- 

 panied by any explanation. 



The figures are of interest as show- 

 ing the form which a balloon takes 

 when forming itself into a parachute, 

 and give some indication of ihe resist- 

 ance oflerefl by the ai r. The parachute 

 was doubtless of an imperfect form, 

 and offered too great a resistance. It 

 had, moreover, the fault of not having 

 a central opening, on which account 

 the air could only escape laterally, and 

 gave rise to the fearful oscillations. 

 In an actual parachute the central hole, of large size, 

 allows easy escape to the air, and the oscillations are 

 slight. It can almost be said that the resistance of a 

 parachute increases with the size of tlie opening. 



The balloon tore on its upper side on account of 

 the disproportion in the ropes. The lower part, 

 reversing, formed a closed parachute. It is not sin- 

 gular that the balloon should have taken such strange 

 shapes while falling. 



AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



ADDRESS OF THE RETIRING PRESI- 

 DENT, DR. J. W. DAWSON, AT MIN- 

 NEAPOLIS, AUG. IS, 1883. 



SO.ME UNSOLVED PROBLEMS IN GEOLOGY. 



My predecessor in oflSce remarked, in the opening 

 of his address, that two courses are open to the retir- 

 ing president of this association in preparing the 

 annual presidential discourse, — lie may either take 

 up some topic relating to his own specialty, or he may 

 deal with various or general matters relating to sci- 

 ence and its progress. A geologist, however, is not 

 necessarily tied up to one or the other alternative. 

 His subject covers the whole history of the earth in 

 time. At the beginning it allies itself with astronomy 

 and pliysics and celestial chemistry. At the end it 

 runs into human history, and is mixed up with arche- 

 ology and anthropology. Throughout its whole course 

 it has to deal with questions of meteorology, geogra- 

 pTiy, and biology. In short, there is no department of 



physical or biological science with which geology is not 

 allied, or at luast on which the geologist may not pre- 

 sume to trespass. When, therefore, I announce as 

 my subject on the present occasion some of the lui- 

 solved problems of this universal science, you need uot 

 be surprised if I should be somewhat discursive. 



Perhaps I shall begin at the utmost limits of 

 my subject by remarking that in matters of nat- 

 ural and physical science we are met at the outset 

 with the scarcely solved question as to our own 

 place in the nature which we stiuly, and the bear- 

 ing of this on tlie difficulties we encounter. The 

 oiganisni of man is decidedly a part of nature. We 

 place ourselves, in this .aspect, in the sub-kingdom 

 vertebrata, and class mammalia, and recognize the 

 fact that man is the terminal link in a chain of 

 being, extending throughout geological time. But 

 the organism is not all of man; and, when we 

 regard man as a scientific animal, we raise a new 

 question. If the human mind is a part of nature, 

 then it is subject to natural law; and nature in- 



