AND OTHER METEOROLOGICAL INSTRUMENTS, BY PHOTOGRAPHY. 
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Description of the Plates. 
PLATE V. 
Fig. 1. A sketch of the complete apparatus, as used in combining the registers of the 
declinometer and barometer. The combination of two piano-cylindrical 
glass lenses, as used in obtaining the register fig. 8, Plate IX., is here re- 
presented. 
Fig. 2. A sketch of the barometer side of the apparatus, with lamp, &c. The cylin- 
drical water lens, as originally used, is represented in this figure. 
Fig. 3. A sketch of the lamp in its stand, to which the fine slit is attached. 
Fig. 4. A section of the burner, the wooden socket, through which it passes, the 
chimney and the diaphragm ; one-half the real size. The top of the burner 
should stand from 0'22 to 0*25 inch below the aperture in the diaphragm, 
and the wick should rise from 0’04 to 0*05 inch above the top of the burner. 
The illuminating power, and steady burning of the lamp without smoking, 
entirely depend on the correct adjustment of these distances, if the cam- 
phine is not oxidized by too long keeping. 
Fig. 5. A sketch of the diaphragm, full size, showing a notch or depression of a 
portion of the edge intervening between the flame and the slit, for the pur- 
pose of allowing the passage of rays from all the most luminous portion of 
the flame, some part of which is below the level of the edge of the diaphragm. 
Fig. 6. A plan and elevation of the diaphragm, full size ; to show the size and posi- 
tion of the aperture. 
Fig. 7 - An elevation of the adjustible slit. As this is in contact with the chimney, 
its support necessarily becomes very hot ; and in order to diminish the 
transmission of heat to the lamp, a space of about 0T inch is left between 
the support and the ring of metal described as surrounding the burner ; 
the wings represented in this figure intercept the light that passes through 
the space here mentioned. - 
Fig. 8. The friction wheels which support the axis of the horizontal cylinders. 
PLATE VI. 
Fig. 1. A side view of the cylinders and time-piece, showing their connexion, and an 
elevation of the barometer, showing the several parts described. If the 
registers of the balanced magnetometer and barometer are combined as pro- 
posed, the relative positions of the index, its slit, and the cylinders will remain 
the same. 
Fig. 2. A side view of the barometer. 
Fig. 3. An elevation of the dial and hands of the time-piece, showing the fork at the 
MDCCCXLVII. 
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