88 Intelligence and Miscellaneous Articles. 



about three hundred and sixty-five yards horizontally over the town 

 of Sandwich," by W. H. Weekes, Esq. 



A Letter addressed to J. P. Gassiot, Esq. from H. Coller, Esq., 

 describing some experiments, not altogether unsuccessful, in copying 

 a Daguerreotype Plate by electrotype. 



The date of the experiments was March 1840. The Plates obtained 

 were on the table. 



" A Register of the electric state of the Atmosphere in relation to 

 its Meteorological Phamomena, for the month of May 1841, from 

 observations made with the insular apparatus already described," by 

 W. H. Weekes, Esq. 



This register, which will be supplied regularly, will be of great 

 value on account of the mode of obtaining the data it contains. 



The reading of a communication from Andrew Crosse, Esq., Mem. 

 Elec. Soc, and another from Thomas Pine, Esq., was deferred to the 

 next meeting. ______ 



LONDON INSTITUTION. 



At a meeting of the Managers of the London Institution, on 

 Friday, June 4th, Sir Thomas Baring in the Chair, Professor Grove 

 showed the electric spark as produced by the condensation of effluent 

 steam,the original experiments on which subject have already appeared 

 xn our journal. At one extremity of a brass insulated conductor was 

 suspended a copper plate of about 7 inches diameter : the jet of steam 

 issuing from a tube connected with the boiler of a^model low-press- 

 ure steam-engine, impinged upon this plate, and several sparks of a 

 quarter of an inch in length, were drawn from the conductor. The 

 electricity of the conductor was shown to be positive. A Leyden 

 phial was charged, &c. We understand that it is the intention of 

 Professor Grove to repeat in the theatre of the Institution any novel 

 scientific experiments which may be capable of popular illustration. 



XVII. Intelligence and Miscellaneous Articles. 



TWO LETTERS ON CALOTYPE PHOTOGENIC DRAWING, FROM 

 H. F. TALBOT, ESQ., F.R.S., TO THE EDITOR OF THE LITE- 

 RARY GAZETTE. 



Dear Sir, — T T is now two years since I first published a brief ac- 

 ■*■ count of Photogenic Drawing. During this interval 

 I have taken much pains, and made many experiments, with the hope 

 of rendering the art more perfect and useful. In this way I have 

 obtained a good many improvements, with the mention of which I 

 shall not detain you at present. 



I shall confine myself in this letter to a single subject, viz. the dis- 

 covery which I made last September of a chemical process by which 

 paper may be made far more sensitive to light than by any means 

 hitherto known. It is not easy to estimate exactly how far this in- 

 crease of sensibility extends ; but certainly a much better picture can 

 now be obtained in a minute than by the former process in an hour. 



