40 FEDERAL REPORTER.
wings or projecting longitudinal flanges attached to the outside of the
screen. The specification states that the riddle or screen, D, in its "con-
struction and operation," is substantially the same as that described in
· a previous patent, granted April 23, 1867, to David Furnier. That this
is so, is evident upon comparing the two patents; and it may be added
that in the Furnier apparatus the cylindrical screen is provided with
· ` exterior wings or longitudinal flanges like those above mentioned, and
performing the same function. The vessel, C, and the receptacle,
. F, are partly sunk below the surface of the stream in which the
dredging-boat is operating, and the inflowing supply of water to the
vessel, C, (to take the place of that swept out of it with the washed
sand) is obtained by means of openings or holes in the side of the
vessel below the water-line. Of this feature of the apparatus the
specineation thus speaks:
" The riddle or screen, D, is placed in a vessel, O, into which is constantly
flowing through openings, m, currents of water, whereby the lower portion of
the riddle, D, is always immersed in water, and a current of water is con—
stantly liowing through the riddle, thereby keeping the meshes of it clean."
There are four claims. The first is as follows:
"A screen or riddle immersed in a vessel of water, and through which is
flowing a stream of water, in combination with an ordinary dredging-boat
for supplying the said screen with unwashed sand, substantially as herein de-
scribed, and for the purpose set £orth."
The second claim is for the same combination, with the addition of
elevators for supplying and charging into the interior·of the screen
runwashed sand. The third claimis for the same combination as the
second, with the addition of a receptacle for receiving the washed sand
and elevators for conveying it therefrom. In each of these claims
occurs the language, "a cylindrical screen immersed in a vessel of
water." The_ fourth claim is for the combination of the screen, D,
the vessel, C, the receptacle, F, two elevators, and four designated
chutes.
It is quite clear to me, from the descriptive portion of the speein-
cation, that the inventor regarded it as essential to the desired end
that the water in which the screen rotates should be segregated by an
inclosing vessel. I The riddle or screen, he instructs - us, is to be
"pLaccd in a. vessel into which is constantly yiowing, through openings, cc,
currents of water, " etc. He perhaps thought that unless the water
was thus cut off from the body of the stream the sand would be washed
out of the screen by the action of the natural current, or by reason
of the agitation of the water. But with his conjectures we need not
concern ourselves. It is enough that by his explicit language, "a rid-
dle or screen immersed in a vessel of water," is a constituent of the
several combinations claimed. Tate v. Thomas, 30 O. G. 345; S. C.
22 FED. REP. 660.
Now, indisputably, the defendants’ screen is not immersed in a ves-
sel of water, nor placed in any vessel whatsoever. On the contrary,