GRAND CURRENTS OF ATMOSPHERIC CIRCULATION. 
673 
that there must be a heaping up of the top layers of the atmosphere to a maximum 
height at about the parallel of 28° and a “ depression ” of them over the Equator, and 
also a “ depression ” of them at and around the poles and in high latitudes generally, 
and his diagram is purposely drawn to represent these features. 
What has now been said is enough to give a good general idea of Ferrel’s scheme 
of Atmospheric Circulation of 1856. His assumptions, his reasonings, and his 
conclusions are, I may say with confidence, pervaded by impossibilities and incon¬ 
gruities. But notwithstanding this his paper is deserving of credit for the praise¬ 
worthy efforts it manifests towards a more complete consideration of important 
principles bearing on the subject, which had previously been unknown or neglected 
or imperfectly touched upon by others. 
While I have told of this paper by Mr. Ferrel at the present stage in order of 
dates, yet I deem it right to explain here that I had no knowledge of its existence, 
nor of any of its author’s views, until some years after the publication of the new 
theory by myself, about which I have to tell forthwith in the present paper. 
Through a paper* read before the Natural History and Philosophical Society of Belfast 
in 1 856, by Mr. Joseph John Murphy, of that town, interest was strongly aroused 
in my mind, in the question of what ought to be supposed to be the true state of the 
case as to the courses of atmospheric circulation in the zonal regions situated between the 
trade-wind zone and the Pole in each hemisphere. In that paper Mr. Murphy brought 
under notice of the Society the scheme of currents of atmospheric circulation set forth 
by Maury, as the truth ; and gave a theory or course of reasoning formed by himself, for 
explaining on dynamic principles how those supposed motions should be accounted for. 
On the subject so presented for consideration, I had to judge that Mr. Murphy’s 
course of reasoning was not valid for sustaining Maury’s theory of the atmospheric 
motions, and I had to judge moreover, that Maury’s theory was itself, in so far as it 
dealt with the circulation outside of the trade-wind zones, entirely untenable and 
impossible. 
Mr. Murphy’s course of reasoning, however, included within it one important 
element not limited in its scope to the application made of it in that particular course 
of reasoning. It was the supposition that the low barometric pressure of Polar 
regions and other high latitudes, already discovered as a fact, through observations of 
voyagers and others, was to be regarded as due to the centrifugal force of the air 
revolving from west to east throughout the great cap of atmosphere covering the 
middle and high latitudes. 
Having rejected Maury’s theory, and having got the benefit of the valuable 
suggestion just referred to in Mr. Murphy’s paper, I succeeded in framing a new 
theory for the circulation in the regions outside of the trade-wind zones. That new 
theory I put forward in a paper read by me at the meeting of the British Association, 
* On the ‘ Circulation of the Atmosphere,’ by Mr. Joseph John Murphy, Belfast Natural History and 
Philosophical Society, 27th February, 1856. 
MDCCCXCII.—A. 
4 R 
