40 REPORT—1840. 
Extract of a letter from Mr. Redfield to Sir J. F. W. Herschel. 
New York, July 28, 1840. 
S1r,—The interest which you have manifested in the progress of meteorolo- 
gical science encourages me to commit to your care the accompanying plans 
and memoranda relating to American storms and tornadoes. 
The map which illustrates the direction of wind in the great storm of De- 
cember 15, 1839, at noon, with its accompanying schedule of observations, I 
beg you to offer to the British Association at the September Meeting in Glas- 
gow—unless you should deem it inappropriate, or consider some other disposi- 
tion of the same as more desirable—which I submit to your better judgement. 
The sketch of the various directions of prostration found in a section of the 
track of the New Jersey tornado of June 19, 1835, with its schedule of obser- 
vations, was designed to furnish you with some of the evidences of rotation 
found in the track of the tornado. Some distinguishing facts, which are thus 
presented, I deem to have been overlooked by others, or at least misappre- 
hended in their bearing. But, although this single sketch of tornado action 
was thus mainly intended for your private use, yet, on penning some remarks 
to accompany it, I was reminded of the claims which Professor Bache had 
upon me, growing out of my published remarks on the discussion at New- 
castle in 1838; and as the subject is not unlikely to engage attention at the 
ensuing meeting in Glasgow, I have thrown into short compass some of the 
considerations which appear to me to establish the whirling action. 
From these, and various other observations in my possession, I trust to be 
able successfully to meet (if necessary) any objections which have been, or 
may be started against the whirlwind theory, as applicable to gales and tor- 
nadoes. But for this, it is necessary that the objections should be made ina 
printed and responsible form, in order that the true state of the case may not 
be mistaken or evaded. 
As regards the map and schedule of observations for the December storm, 
perhaps I should not have taken the trouble to prepare them, had it not been 
intimated to the public in reference to my former account of this storm, as it 
appeared at sunset, that had the observations been given for the middle of the 
day, the wind arrows at Nantucket, at Cape Cod, and at New Bedford, and 
with the ship Morrison, would all have pointed in towards a central line. 
It has long been my intention to prepare and publish a more full examina- 
tion of the phenomena of the New Jersey tornado and other destructive whirl- 
winds, but my avocations and habits are not the most favourable to the execu- 
tion of this design. I beg you to make such disposition of the paper now sent 
as you may deem most desirable and proper. 
I am, with great respect, 
Your most obedient servant, 
W. C. REDFIELD. 
The documents to which this letter refers were not received in time 
to be laid before the meeting. 
——__—. 
On the Dew-Point. By Dr. ANDERSON. 
The author explained the principles of the formula, which he de- 
duced several years ago from the experiments of Dalton and Gay- 
Lussac, for determining the various objects connected with the hygro- 
metric state of the air; and showed, by means of tables which he had 
constructed from it, the facility and despatch with which the absolute 
