157 
the standard size of pictures, taken by Daguerre in 1835, 
should have been precisely the same as those used by James 
Watt in 1799. However, from the stamp on the corner of 
my plate, the peculiar form of the figure four (4) points it 
out as a French production ; whilst the Soho plates are 
apparently English, rendering the possibility of their exact 
coincidence in size still more improbable. 
“ Speculations on the Process employed by Messrs. Boulton 
and Watt in the Production of the Pictures called by them 
‘Mechanical Pictures.’” By J. B. Dancer, F.R.A.S. 
My remarks at present are confined to the two pictures on 
the table, of human figures, numbered 7 and 8. They 
measure 17xl3| inches, and are identical in size and sub- 
ject. By the kindness of Mr. Sidebotham I have had an 
opportunity of making a minute examination of them. The 
only apparent difference between them is, that No. 7 is in 
plain ink, and in No. 8 the garments of the figures are 
coloured — one red and the other blue. 
I am informed that these pictures are similar to those 
which were supplied by the firm of Boulton and Watt, and 
copies from originals sent to them. They were issued, it is 
said, with tolerable rapidity, and at a very moderate price ; 
but the process by which they were multiplied was kept a 
profound secret. 
At the first glance the pictures look as if they. were pro- 
duced by hand ; but, on comparing them carefully, the close 
resemblance in the drawing in each is found to be so remark- 
able that no artist, however clever, could produce such exact 
duplicates without great expenditure of time. A more 
minute examination by means of a lens shows scratches and 
lines (evidently accidental) which correspond accurately in 
each picture, affording a convincing proof that these copies 
could only be produced by some mechanical or chemical 
agency. 
