SCIENTIFIC SUMMARY. 
229 
aperture or pupil, the character of the humours composing the lenses and 
the field (or retina) covered, when compared with the photographic lens and 
camera, all showed how widely different were the conditions under which 
the two kinds of images were relatively formed. Looking at natural objects 
with the naked eye and then looking at them as thrown by a lens on the photo- 
grapher’s focussing screen was as if the objects had been suddenly conveyed 
into a purer and more strongly illuminated atmosphere. The lights, sha- 
dows, and colours appeared greatly more intense, minute detail became more 
prominently and sharply defined, varieties and degrees of difference in texture 
largely disappeared, distant objects seemed nearer; and however charming 
the effects thus seen might be on the ground glass, they were productive 
of anything but a proper natural effect in the finished photographs. This 
was due, Mr. W all believed, to the condensation of an excessive amount of 
light by large lenses constructed with a view to accelerating the exposure 
of the plate. The remedy Mr. Wall proposed was the adoption of lenses of 
longer focus with smaller apertures or stops and with the use of chemicals 
and other conditions calculated to render the exposures as short as, under 
such circumstances, was possible. A very animated discussion followed the 
paper, and various views were advanced, most of them being more or less 
favourable to the opinions above expressed. 
Mr. Dallmeyer's u New ” Portrait Lens. — This lens is so constructed as to 
give its user the option of either producing a sharp image or one softened, 
or blurred, by being put more or less out of focus. Some writers have argued 
as if this eminent optician, by introducing such a lens, advocated spherical 
aberration as an element of artistic success in photographing. We suspect 
the simple truth to be that Mr. Dallmeyer only desired to produce a lens 
for which there appeared to be a growing demand in the optical market. 
Photography and Electricity. — Mr. William H. Harrison informs us that at 
the present time more than one philosopher of eminence is experimenting pho- 
tographically on comparatively untrodden ground in connection with the rays 
thrown out by electricity in passing through vacuum tubes, such rays being 
rich in photogenic power. 
Photographs of Brass Rubbing. — Mr. 0. G. Rylander has recently giyen 
attention to a new photographic application, by which a large number of 
copies may be obtained from the rubbings from old brasses, it being his inten- 
tion, we believe, to publish them in a volume, for which purpose he solicits 
communications from those who may have a collection of such rubbings. 
Mr. Rylander’s address is 129 Malden Road, Kentish Town. A brass rubbing 
is effected by pressing a sheet of white paper in close contact with the 
monumental tablet and rubbing the upper surface with a small cake of shoe- 
maker’s u heel ball,” while care must be taken that the paper be not dis- 
placed during the operation. By these means the raised parts are blackened 
and rendered opaque and the white parts are more transparent. By using 
this as a negative on paper sensitive to light, a print is obtained in which 
the lines are black on a white ground. 
