■754 



SCIENCE. 



[N. S. Vol. III. No. 73. 



valued friend, Mr. Graham Bell, to author- 

 ize the publication of a general statement 

 of the results thus far obtained. 



Let me add, in explanation, that the scale 

 of the construction did not admit of any 

 apparatus for condensing the steam or 

 economizing the water, which, therefore, 

 could only be carried in sufiQcient quantity 

 for a very short flight. This difficulty is 

 peculiar to the scale on which the experi- 

 ment is conducted, and does not present 

 itself in a larger construction. 



Professor Bell has shown me his letter, 

 which follows. 



Very respectfully yours, 



S. P. Langley. 

 Washington, D. C, May 12, 1896. 



The Editor of Science — Dear Sir : Last 

 Wednesday, May 6th, I witnessed a very 

 remarkable experiment with Prof. Lang- 

 ley's aerodrome on the Potomac Eiver ; in- 

 deed, it seemed to me that the experiment 

 was of such historical importance that it 

 should be made public. 



I am not at liberty to give an account of 

 all the details, but the main facts I have 

 Professor Langley's consent for giving you, 

 and they are as follows : 



The aerodrome or ' flying machine ' in 

 question, was of steel, driven by a steam 

 engine. It resembled an enormous bird, 

 soaring in the air with extreme regularity 

 in large curves, sweeping steadily upward 

 in a spiral path, the spirals with a diameter 

 of perhaps 100 yards, until it reached a 

 height of about 100 feet in the air at the 

 end of a course of about half a mile, when 

 the steam gave out, the propellors which 

 had moved it stopped, and then, to my 

 further surprise, the whole, instead of 

 tumbling down, settled as slowly and grace- 

 fully as it is possible for any bird to do, 

 touched the water without any damage, 

 and was immediately picked out and ready 

 to be tried again. 



A second trial was like the fii-st, except 

 that the machine went in a different direc- 

 tion, moving in one continuous gentle as- 

 cent as it swung around in circles, like a 

 great soaring bird. At one time it seemed 

 to be in danger as its course carried it over 

 a neighboring wooded promontory, but ap- 

 prehension was immediately allayed as it 

 passed 25 or 30 feet above the tops of the 

 highest trees there, and ascending still fur- 

 ther its steam finally gave out again, and 

 it settled into the waters of the river, not 

 quite a quarter of a mile from the point at 

 which it arose. 



K"o one could have witnessed these ex- 

 periments without being convinced that the 

 practicability of mechanical flight had been 

 demonstrated. 



Yours very truly, 



Alexander Geaham Bell. 

 1331 Connecticut Avenue, 



Washington, D. C, May 12, 1896. 



TEE DEVELOPMENT OF EXOGENOUS STRUC- 

 TURE IN THE PALEOZOIC LYGOPODS—A 

 SUM3IARY OF THE RESEARCHES OF 

 WILLIAMSON AND RENAULT. 



The fact of the occurrence of exogenous 

 structure in the Lycopodinese, Equisetinete 

 and some of the ferns of the Carboniferous 

 age is in itself hardly less remarkable and 

 interesting than is the variety of phases un- 

 der which this structure makes its appear- 

 ance. It would seem that during the rapid 

 differentiation and modification of vascular 

 plants at the time of the great coal forma- 

 tion, plants of these lower classes played 

 fast and loose with exogeny, shaping in fan- 

 tastic and capricious designs a structure 

 that is now the garb of the most exalted 

 classes. Even within the boundaries of the 

 Lepidodendra and the Sigillarice the diversity 

 is so great that while some species show no 

 secondary growth at all, others, especially 

 among the Sigillarice, are so highly organ- 

 ized that the followers of the Brongniartian 



