482 



SCIENCE, 



[Vol. IV., No. 94. 



A third edition of his well-known volume, entitled 

 ' Popular scientific addresses,' having been called for, 

 the author seized the opportunity to complete the. 

 collections, and in doing so has dropped the word 

 ' popular,' although the earlier and later papers are 

 alike designed to bring the results of mathematical, 

 physical, and other scientific researches, before a cir- 

 cle of hearers and readers whose studies do not run 

 in that direction. Among other papers, the volumes 

 contain Helmholtz's prefaces to the German edi- 

 tion of Thomson and Tait's 'Natural philosophy,' 

 and of Tyndall's ' Fragments of science, ' and also his 

 academic discourses. Among other noteworthy pa- 

 pers is an address on electrical units in reference to 

 the action of the Electrical congress at Paris in 1881. 

 This address, which was given in Berlin in December 

 of that year, was reported, at the time of its delivery, 



in Carlsruhe, has been called to the professorship of 

 physics at Tiibingen. Dr. O. Liidecke has been ap- 

 pointed professor in the philosophical faculty in the 

 university at Halle. 



— The German association of naturalists has se- 

 lected Strassburg for its next year's assembly. 



— The completion of the Lick observatory now 

 depends upon the successful making of the disk of 

 glass for the objective of the large telescope. The 

 main dome cannot be made till the focal length of 

 the large equatorial has been determined. 



— The success of the flying-machine invented by 

 Kenard and Krebs has called attention to a partially 

 successful experiment tried at the military experi- 

 ment-station at Chalais-Meudon in 18*79. The con- 



AEliuPlANE INVENTED BY VICTOK TATIN. (La Mature.) 



stenographically, and has now been revised, and sup- 

 plemented by a statement of the conclusions of the 

 conference of 1884. 



— Professor Valentine Ball of Dublin writes to 

 Nature, lamenting the few copies of the English gov- 

 ernment scientific reports which are gratuitously 

 distributed in the United States. He states, that 

 although from a feeling of shame he did not seek to 

 gather statistics, he found from casual conversation 

 that a great many of the American libraries were 

 obliged to purchase such reports as those of the vari- 

 ous English surveys and the Challenger expedition. 

 He praises the lavishness of our own government 

 bureaus and the work of the Smithsonian in the dis- 

 tribution of printed matter, and expresses a hope 

 that some similar free bureau of exchange may be 

 established in England. 



— Prof. F. Braun, formerly at the Polytechnikum 



s traction of the machine, an invention of Victor 

 Tatin, is pictured in a general way above. It con- 

 sisted of a cylindrical receiver for compressed air, 

 which was used to drive two air-propellers. The 

 weight of the whole was supported by the pressure 

 of the air against the under sides of the laterally ex- 

 tended wings, the forward edges of which were kept 

 inclined slightly up by the steering-action of the tail. 

 The total weight of the apparatus, as tried, was 1.75 

 kilograms, and the velocity obtained, about 8 metres 

 per second. The machine was able to rise from the 

 ground; and, attached by a cord to a post, it flew 

 around in a circle, passing over the head of the spec- 

 tator (seep. 481). Mr. Tatin sent a description of his 

 experiments to the French academie des sciences, in 

 competition for the Perraud prize, and 'received a 

 reward, as did Gaston Tissandier for his experiments 

 on the application of electricity to aeronautics, and 

 Duroy de Bruignac for his aerophone mixte. 



