226 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



beautifully. Precce has described two phonographs made 

 in England from Edison's descriptions. In one of these the 

 rotation was rendered uniform by means of clock-work, thus 

 maintaining the identity of the sounds ; in the other the 

 receiving membrane was of paper, and seemed to be the 

 loudest. 



Blake has devised and practically applied a very ingenious 

 method of recording articulate vibrations by means of pho- 

 tography, and has obtained some very interesting results. 

 The apparatus consists of a mirror of steel capable of oscillat- 

 ing about a diametral axis, to the back of which is attached 

 a lever, by which it is attached to the centre of a telephone 

 disk, arranged with the usual mouth -piece contrived by 

 Peirce. Whenever the disk is caused to vibrate, the mirror 

 oscillates with it, and a beam of sunlight thrown on the mir- 

 ror from a heliostat describes lines of light on a suitably 

 placed screen. If this screen be movable at right angles to 

 these lines of light, and carry a sensitive collodion film, the 

 light oscillation is recorded upon the prepared surface as a 

 more or less complex curve having the peculiarities of the 

 sound-wave which caused it. Representations of the curves 

 of various sounds accompany the paper. 



Pfaundler has given, in a communication to the Vienna 

 Academy, the results of some physiological experiments to 

 determine the question whether two isolated sound-pulses 

 can produce a sensation of tone, either alone or by repetition'. 

 His first experiments were undecisive, but upon repeating 

 them with the aid of Baumgarten's reflection-tones, he was 

 able to answer the above question in the affirmative. Sub- 

 sequently, using a siren with two air openings, analogous to 

 Baumgarten's method, he confirmed his results. 



HEAT. 



Victor Kegnault, whose death took place on the 19th of 

 January, 1878, was a man of the highest scientific eminence. 

 Born at Aix-la-Chapelle in 1810, he entered the store of a 

 draper in Paris, and at twenty the Ecole Polytechnique, 

 where he remained two years. He then went to Lyons, oc- 

 cupying the chair of chemistry, and worked at research so 

 successfully that in 1840 he was elected to the French Acad- 



