REDFERN, ON AQUARIA. esi 
narrow ring sliding easily on the vertical stem, and composed 
of two short sections of tube, one within the other. The 
inner piece is cut entirely through at the spot d; and at the 
opposite side, e, it is soldered to the outer one. Through the 
outer of these pieces the screw, f, works upon the inner one, 
tightening it and fixing the ring, c, at any height upon the 
vertical stem. 
g is a piece of tube three inches long, and split at the ends 
so as to slide and rotate easily on the vertical stem, 4, on 
which it can be supported at any height by the ring, c, which 
is below and unconnected with it. # is another piece of 
the same tube as g, placed at right angles across it, and 
rotating upon it. The joint between g and / is the only 
part of the apparatus which requires a brass casting to be 
made specially for it; all the other parts should be made of ~ 
such materials as are used for gas fittings. It consists of a 
thick circular dise of brass, an inch and a half in diameter, 
soldered to the tube, g, on one surface, and accurately turned 
in a lathe on its edge and the other surface, so that it may 
fit very tightly imto a cap turned like itself, but soldered to 
the tube, 2. These two parts fit each other like two of a 
series of nested apothecaries’ weights. Between them a 
leather washer is placed im a turned groove, and they are 
then screwed firmly together by a large screw inserted and 
turned through the hole, 7, cut in the front of the tube, h. 
I found that however tightly this screw might be turned, 
the joint, in which there is an exceedingly smooth motion, 
was too loose, and I therefore got the pinching screw, 4, 
