178 Miscellanies. 



and hence the necessity of getting quit of the mirror placed in cameras, 

 for throwing the representation in such a way as to allow of its being 

 traced by the artist. Hence, in taking impressions by the camera, the 

 prepared paper must be fixed on the hack of the box, directly opposed 

 to the lens, and the focus properly adjusted. I have found great ad- 

 vantage, in taking impressions by the camera, in using the paper moist, 

 and keeping it so all the time it is exposed. For this purpose, after 

 moistening it, I place it between a cushion and a pane of glass, tied 

 tightly together, to prevent, as much as possible, the escape of mois- 

 ture. In this way I have succeeded in a few minutes in getting a faint 

 outline of the object exposed to the lens. 



I may here mention that the camera affords a good method of ta- 

 king profiles from busts, not by the reflected light from the bust, but 

 by interposing it between the lens and the source of light. The bust, 

 for instance, may be placed, during sunshine, at an open window, and 

 the image from it thrown on the prepared paper ; using the precau- 

 tion, of having the face slightly inclined towards the source of light, so 

 as to give its outline as distinctly as possible. 



Etchings. — A method of taking impressions of etchings on glass by 

 the photographic process was described by Havell of London. For 

 this purpose the glass is covered with etching varnish, and after the 

 figure is etched on it, it is smoked, so as to darken the varnish to 

 prevent the transmission of light;^ of course, the smoke does not adhere 

 to those parts of the glass exposed by the etching needle, and is there- 

 fore easily wiped off with a cloth, thus leaving the etching free for the 

 light to pass through. On exposing this with the prepared paper be- 

 hind it, a beautiful impression is taken. In taking impressions in this 

 way, the varnished side must be placed next the paper, which must 

 be kept close upon the etching by means of a cushion, otherwise the 

 impression is not well defined. When the glass side is next the paper, 

 the impression is very indistinct, owing to the light, when it passes 

 through the exposed parts of the glass, being diffused, and by which the 

 lines run into each other. 



From the ease with which impressions can be got in this way, it oc- 

 curred to me that the process might be still farther extended, so as to 

 enable us to take copies of oil paintings, or of drawings on boards, 

 through which the light does not penetrate, and for this purpose I 

 have followed different methods. One of these is to cover the glass 

 with a transparent varnish, as Avith a thin solution of Canada balsam 

 in oil of turpentine, and, after laying it down on the oil painting, to 

 etch it out on the varnish, in the usual way ; after this, the glass is to 

 be slightly heated, so as to soften the varnish, which is then to be 

 smoked, by holding it in the flame of an argand gas lamp, taking care 



