nder which objects should be taken
when near, moderately distant, or far removed from the camera; stating, at
the same time, at how many feet from the camera an object is to be
considered as near, or distant, or between the two? It would be a great
assistance to beginners in the stereoscopic art, if some experienced
gentleman would state the best distances and angles for taking busts,
portraits, groups, buildings, and landscapes.

It is said that stereoscopic pictures at great distances, such as views,
should be taken "with a small aperture." But as the exact dimensions are
not mentioned, it would be equally serviceable if, to the other details,
were added some account of the dimensions of the apertures required for the
several angles.

In the directions given in the work from which I have quoted, it is said
that when pictures are taken with one camera placed in different positions,
the angle should be 15 deg.; but when taken with two cameras, the angle should
be 10 deg. Is this right? And, if so, why the difference?

In the account given by you of Mr. Wilkinson's ingenious mode of levelling
the cameras for stereoscopic pictures, it is said the plumb-line should be
three feet long, and that the diagonal lines drawn on the ground glass
should be made to cut the principal object focussed on the glass; and "when
you have moved it, the camera, 8 _or_ 10 feet, make it cut the same object
again." At what distance is the object presumed to be?

Any information upon the above matters will be a great service, and
consequently no slight favour conferred upon your constant reader since the
photographic correspondence has been commenced.

[phi].

_Photographic Portraits of Criminals, &c._--Such experience as I have had
both in drawing portraits and taking photographs, impels me to hint to the
authorities of Scotland Yard that they will by no means find taking the
portraits of gentlemen that are "wanted" infallible, and I anticipate some
unpleasant mistakes will ere long arise. I have observed that inability to
recognize a portrait is as frequent in the case of photographs as on
canvass, or in any other way. I defy the whole world of artists to reduce
the why and wherefore into a reasonable shape; one will declare that
"either" looks as if the individual was going to cry; the next critic will
say he sees nothing but a pleasant smile. "I should never have known who it
is if you hadn't told me," says a third; the next says "it's