Proceedi of the B itish { * bi } 371 
Thus according to Mr. Whewell’s method of taking the obser- 
vations, (which he was persuaded was the only true method, ) in 
the latitude of Plymouth, they had something like a trade-wind, 
setting in from southerly to northerly points of the compass at a 
mean velocity of 4$ to 6 miles per hour. This was something 
like a definite result in meteorology; for no person before had 
ever attempted to discover the direction and velocity of the wind 
in its rate per hour, setting in a given direction.* In these state- 
ments he had been dealing only with mean results. 
Mr. Howard hoped that Mr. Harris would not think of discon- 
tinuing these observations until at least the cycle of 18 years had 
been completed.—Col. Sykes believed that the hours of maximum 
and minimum mean pressure observed by Mr. Harris at Plymouth, 
would be found nearly, if not exactly, the same as those obser- 
ved in India at an elevation of 2000 feet above the sea, and those 
observed in Mexico, by Humboldt, 10,000 feet above that level.— 
Col. Sabine said, he had that morning received a very important 
letter from Prof. Wheatstone, containing a proposal to make, for 
the Observatory at Kew, an apparatus which should record the 
operations of all meteorological instruments so as to effect a great 
saving of cost. One of the instruments was for measuring the 
force and direction of the wind, and was capable of being sent 
up in captive balloons, so that the currents, to a height of 8,000 
or 10,000 feet, might be carefully examined. All attempts to 
make self-recording thermometers, barometers, &c. by mechani- 
cal means, have hitherto failed, because the mechanical force ex- 
erted by the rise of the mercury in the tubes, is insufficient to 
overcome the friction of the attached mechanism, and only very 
inaccurate indications can be obtained. The principle however, 
(observes Mr. W.) which I employ in my meteorological telegraph, 
viz. the determination (by means of a feeble electric current) of 
any required mechanical force by the mere contact of the mer- 
». cury in the tube with a fine platina wire, enables all these diffi- 
~ culties to be overcome. I propose, therefore, that such an instru- 
: ment, the cost of which I estimate will not exceed £50, shall be 
constructed under my direction for the Richmond Observatory. 
gu after a few months’ trial at the Observatory, it shall be found 
~ * See Prof. Loomis’s ee regarding the progress of the wind at Hudson, 
Ohio: this Jour. Vol. 41, p. 
