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XII. A Compact Arrangement for Reading of Deflexions 
(of Galvanometers, &c.), with the Possibility of Increasing 
the Sensitiveness without Increase of Space or Loss of Light. 
By J. J. Taupin CHasor™. 
° aa light from the scale, 1, is received by the mirrors 2 
and 3, the instrument mirror 4, the totally reflecting 
prism 5, and on passing through the telescope 6 reaches the 
eye of the observer. 
The instrument mirror moves about vv as axis, while the 
mirrors 2 and 8 are maintained in continuous rotation about 
the same axis, and in such a manner that by means of double- 
reduction toothed gearing, «7, the mirror 2 is given x times 
(where 7 is an integer) the angular velocity of the mirror 3 
about xa. 
The mirrors 3 and 2 may be driven pneumatically by 
means of a foot bellows, the compressed air driving a small 
turbine wheel carried by the axle of the mirror 3; the speed 
need only be high enough to produce a continuous picture of 
4 
the scale by means of what are in reality intermittent flashes of 
light ; a small regulating stop-cock is for this purpose fitted 
to the air-supply pipe. The whole forms a very easily and 
* Communicated by the Author, 
