frame of the truck itself. After the grant of that patent
various improvements were made by persons interested in the
subject. In the under-frame an improvement was made by
which the under-frame could be raised or lowered, and the
wing spreaders were attached to the under-frame, with the
result that the vertical distances of the wing spreaders from
the deck of the truck, and also the angle at which the frames
were in respect of the trunk, could be varied. Moreover another
invention had been added. A sort of shovel had been attached
to the front of the truck which could be raised vertically, and
which scooped off the earth in front. What was called a central
spreader was attached to the front of the truck which could
be raised vertically with the under-frame, but the under-frame
to which that was attached was not the same as that to which
the wing spreaders were attached. There is therefore this differ-
ence, that the earlier contrivance had a central spreader in front
of the truck, whereas in that described in the present applica-
tion the spreader is underneath the truck. The two things are
therefore not identical in form, though they are very much
alike, and are intended to perform exactly the same functions.
The differences may be in practice infinitesimal, or they may be
considerable. But there is certainly this difference, that the two
wing spreaders and the central spreader in the one are attached
to two separate under-frames, and in the other are attached to
the same under-frame, the consequence being that in the one
raising the under-frame raises the whole spreading appliance,
while in the other there are two frames to be raised. There is
another minor modification, that the central spreader being
attached to the same under-frame to which the wing spreaders
are attached can be raised and lowered on a batter, whereas in
the modification of the original patent which was already in use
this central spreader could only be raised vertically. Under
these circumstances are we to say that one invention is practic~
ally the same as the other? In consideration of these cases it is
important to consider, first of all, the nature and subject-matter
of the invention. It was pointed out in Clark y. Adie (1), and
in other earlier cases, that in the case of a combination it is no