84 
The negative taken direct in the telescope is but one step 
towards what we require, that is, the enlarged copy on paper. 
From the small negative a positive on glass must be made, 
say of twice or three times the diameter of the original. It 
will be quite unnecessary here to explain how the enlarge- 
ment is to be made; but I may remark that the negative 
should be placed with the film side towards the copying lens, 
and the resulting positive copy must also be placed in the 
same way. The enlarged copy or negative will then give 
the true telescopic appearance of the moon. In the print of 
the full moon by Mr. Rutherford a mistake has been made, 
arising from the negative or positive copy having been placed 
the wrong way, and consequently the moon looks as if it had 
been photographed from the opposite side. The print is a 
very beautiful one in other particulars, but entirely worthless 
as a picture of the moon, as the eye can never see it as there 
represented. 
I have sometimes taken two negatives on the same plate. 
It will be seen in the drawing that the dark slide is not quite 
central with the telescope, so that by reversing the plate after 
one exposure a second picture can be taken. In photograph- 
ing the planets Mr. De la Rue has allowed the object to move 
on for a few seconds, the telescope meanwhile being at rest, 
and thus four or five negatives can be taken in a very short time 
on the same plate. It has occurred to me that by having a 
frame made “ landscape way” instead of upright, and in place 
of having four clips such as K, there might be a kind of 
groove at top and bottom, so that after taking the first 
negative, and the light shut off, by moving the plate about an 
inch, at least three negatives might be taken on the same 
plate — or a “ shifting back” might he adapted. The advan- 
tages of this plan are that different exposures might be tried, 
and the development continued for the one or two which 
promised the best results. This method would effect a great 
saving of time, which on a fine night is of much importance. 
With the Barlow lens I have made some negatives which 
