ion of glue and molasses came
into general use, and this important invention was of great assistance
in the further improvement of the printing press.

Other cylinder presses with mechanical inking appliances were devised
and patented, the most notable of which were those of Rutt, Bacon,
Cowper, Applegath, and Napier, but the mechanical imperfections of
these presses unfitted them for the better grades of book printing.

Further efforts were, therefore, directed to increasing the output of
the bed and platen presses by the application of improved inking
devices, sheet-feeding, and impression mechanisms. About 1825 there
was constructed by D. Napier, a machinist in London, a press
containing such appliances which produced six to seven hundred
impressions an hour. Other presses constructed upon the same
principle, but with two type-beds, two sets of friskets, two inking
mechanisms--and only one platen, in the centre of the press--were made
by Hopkinson & Cope and by Napier, and were known as "double platen
machines," though this is really a misnomer as there was only one
platen.

Napier's invention achieved the greatest popularity and came into
general use. At each end of his press there was an inking device, a
type-bed, and a frisket, each set of which operated alternately with
the other, but either could be made inoperative if the "feeder," or
"layer-on," failed to place the sheet in time. Four boys, besides the
printer, were required--two to lay on, and two to take off the sheets.

When the type-bed and the frisket carrying the sheet of paper were in
position under the platen, the latter was drawn downward to make the
impression by means of a "toggle" joint which acted upon two strong
rods, one on each side, and was then raised again by a counterbalance
weight. Owing to the awkward method of handling the paper, the working
speed of the press was necessarily slow, and the size of the sheets
limited to double royal, or 25 x 40 inches.

The best presses of this type were those devised and patented by Isaac
Adams, of Boston, in 1830 and 1836, and by Otis Tufts, also of Boston,
in 1834. R. Hoe & Co., of New York, acquired Adams' business in 1858
and continued the manufacture of his presses. Over one thousand in
many different sizes were made by this firm, the largest printing a
sheet 33 x 46 inches at a working speed of one thousand impressions an
hour. The last Adams press was made in 1882, but quite a number are
sti