414 THIRD REPORT — 1833. 



On the Construction of a New Baro?neter. By the Rev. W. H. 

 Miller, F.G.S., Professor of Mineralogy, Camhridge. 



This barometer consists of two tubes, of equal diameter, a 

 little longer than the greatest height and greatest range of the 

 barometric column respectively, terminating in a small cistern, 

 the bottom of which can be elevated or depressed by a screw. 

 The long tube is bent so that the upper part of it, which is 

 closed at the end and has a fine point of glass or steel fixed 

 in its axis, may coincide with the prolongation of the short 

 tube, which is open at the end. A graduated scale slides along 

 a vernier attached to the frame of the instrument, in such a 

 manner that a steel point fixed to the lower end of the scale 

 may move in the axis of the short tube. 



In making an observation with this instrument, the bottom 

 of the cistern must be elevated or depressed till the surface of 

 the mercury in the long tube touches the fixed point therein : 

 the moveable point on the scale being then brought down till 

 it touches the surface of the mercury in the short tube, the 

 height of the barometric column is indicated by the division of 

 the scale opposite to zero on the vernier. The barometer may 

 be rendered portable by placing a stopcock between the short 

 tube and the cistern. 



On a Barometer with an enlarged Scale. By William L. 



Wharton. 



In this barometer a light fluid is introduced upon the top of 

 the mercurial column of the common barometer, the tube of 

 the instrument being enlarged at the point of junction of the 

 two fluids, by which device an instrument of equal or superior 

 extent of scale may be obtained, without the expense and dif- 

 ficulty attendant upon the construction and erection of a baro- 

 meter of which the whole tube is occupied by the light fluid. 

 Mr. Wliarton has employed an instrument of this construction 

 for twelve years without perceiving that its sensibility is at all 

 impaired. 



On the Construction of a new Wheel Barometer. By 

 William Snow Harris, F.R.S., 8fc. 



The tube of this instrument is 0*5 of an inch in diameter 

 within, bent in a siphon form at one end, and at the other ex- 

 panded into a flattened spheroidal bulb, whose diameter is 

 four inches, and axis, in the direction of the tube, two inches. 



