3S2 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



The chairman presented the following' memoranda of science and art : 



The Chinenti Pictdres. 



These pictures were made by I. Chinenti before the year 1640. Dr.- A. 

 C. Brown saw them in the Muse-jm at Lille, in 1859, and first announced 

 them to be stereoscopic. Sir David Brewster asserts that Baptista Porta 

 published in 1593 the true principle of the stereoscope, and that Chinenti 

 executed drawings from the binocular principle of Porta and was the inven- 

 tor of stereoscopic pictures. Mr. Wheatsime obtained photographs of the 

 Chinenti pictures and declared they were not stereoscoj>ic. Prof. Enierson 

 of Troy, published his cor elusions from an investigation of the subject, 

 which were controverted by Sir David Brewster in a letter to the Philo- 

 sophical Magazine, for January. 1804. As the point in dispute could only 

 be settled by the testimc-ny of those persons skilled in stereoscopic investi- 

 gations, at the request of Prof. Emerson, some pains has been taken to 

 collect the opinions of several scientific gentlemen in this country. These 

 are embraced in an article by Prof. Charles A. Joy, in the last number of 

 Silliman's Journal, and are all opposed to the position taken by Sir David 

 Brewster. 



Inductive Electric Currents. 



M. Soret has reported to the Paris Academy of Sciences the results of his 

 researches in relation to the exterior action of an electric current. He finds 

 that whether the inductive current is continuous, or is broken by the Rulmi. 

 KorflF coil, the electrolytic law is tlie same, and that the deposit of copper 

 in the voltajueter is directly as the intensity of the current. 



New Process of Engraving. 



A recent invention of M. Dulos is described in the Moititeur Srientifique 

 as follows: A copper plate, on which a design has been traced, in litho- 

 graphic ink, receives, by the action of galvanism, a deposit of iron on the 

 parts untouched by the ink. The ink having been removed by benzine, the 

 white portions of the design are represented by the layer of iron, and the 

 black by the copper itself. The plate is then plunged into a bath of cya- 

 nide of silver under a galvanic current, and the silver is deposited on the 

 copper onl3^ In this condition mercury is poured over the plate, which 

 attaches itself to the silver only, appearing in relief and taking the place 

 of the lithographic ink. A plaster or wax mould is then taken, and by 

 metalizing it bj' electrotyping, a matrix is obtained from which impressions 

 on paper may be produced by the ordinary copper plate press. For typo- 

 graphic engraving, in which the design is in relief, the plate of copper 

 should receive, on leaving the hands of the designer, a layer of silver, de- 

 posited only on the parts untouched by lithographic ink. The ink is 

 removed by benzine, and those parts of the plate that were inked are 

 iodized and the above treatment is continued. In this way the raised de- 

 sign is produced. Several improven)euts on the process are said to have 

 been since made by M. Dulos, one of which is to substitute for mercury a 

 fusible amalgam of copper. 



Photographical. 



M. Regnault states that a plate of copper dipped into a solution of bich- 



