184 MEASUREMENT OF HIGH TEMPERATURES. [bull.54.J 
filled with fitting knife edged blades of steel, or with asbestus board, 
against which the screws t press. All of these methods are good. 
Even when tbe temperature is so high as to fuse the inner surface of 
the collar the screws t can be worked loose with a drop of oil or petro- 
leum, and after removal show no serious injury. It is not easy to fit 
the axle of the muffle into the iron collar, because the silicious material 
does not yield easily to the file. It may, however, be ground on a grind- 
stone, or, with greater advantage, by filing it with a piece of its own, 
substance. 
Having thus shown how to fasten the collars symmetrically, and at) 
such a distance apart that the opposed flanges may fit in the grooves on 
tbe opposed rollers Q, Q and Q', Q', it is next in order to describe the; 
adjustment of tbe rollers themselves. Their axles, R, R, R', R', are! 
mounted at suitable distances apart on a rectangular rod of cast-iron, j 
u u, provided with a handle of wood, W. The rods u u, u' u' again! 
are each adjustably fastened to Y shaped uprights Y, Y, Y, Y, 1 and Y',j 
Y', Y', Y' by aid of strong screws T 7 , V. Loosening For V tbe rod! 
u u or u' u' may be raised or lowered or rotated around the center of 
V or V and clamped in any desired position. It is in this way that the! 
inner edge of the collars N N N JV, N' N' N' N' may be nicely adjusted] 
with reference to the lateral shouldered holes of the furnace through] 
which the axle of the muffle projects. Rotation therefore takes placei 
on tbe friction rollers, in which the wheel or flange P P rolls smoothly.] 
It will be seen that some such arrangement as this is essential, for the 
rolling parts must be placed so far away from the hot parts that tbeyj 
may be lubricated. At very high temperatures the muffle becomes 
more or less viscous, and hence it is necessary to obviate all such ten-j 
dencies to twist or wrench off the axles as an imperfectly oiled mecban-; 
ism constantly presents. There is one further adjustment to be made: 
After the firing neither do the axles of the muffles coincide in prolonga 
tion, nor are the axes of the cylinders straight lines. Hence the axle 
of the rollers R R, R' R' are long cylindrical rods along which the 
rollers Q Q Q Q may slide laterally, their extreme positions being fixed, 
by four adjustable set-screw collars x, x, x', x'. 
To revolve tbe muffle a belt pulley of wood Z Z has been screwed to 
the flange-wheel P' at a little distance from it. Over this passes round- 
leather belting, and the power is communicated by a correspond! ng 
pulley on a lateral shaft of the engine. The wooden belt-ring Z Z is far 
enough away from the hot parts to escape being charred. The belt J 
however, must be provided with a tightener. 
1 The uprights were given tbe Y-shaped form to prevent the possibility of Literal, 
slipping of the muffle. In later experiments I found this safeguard unnecessary, .so 
that a simple Hat upright, with a vertical slot opening upward to admit the screws 
V, V, is far preferable. In other words, the uprights in the figure are to be sawed 
off square above the slot. By this means greater facility of adjustment is secured; 
wheu the collar is to be fitted to the axle of the muffle or removed from it. 
(838) 
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