40 REPORT — 1856. 



application of these views. — Prof. Hennessy then proceeded to show that the 

 isothernials of Ireland strictly conformed to his theory. On discussing the obser- 

 vations collected and arranged by Dr. Lloyd in his ' Memoir on the Meteorology of 

 Ireland,' it appears some of its isothermals are actually closed curves, while others 

 terminate at points on the coast, the shortest being closest to the equator. The 

 physical structure of Ireland, and the difference of nearly 4° between the tempera- 

 ture of the seas bathing its shores and the air above them, rendered it probable, 

 d priori, that Ireland should present a good example for the application of the 

 theory. From the general nature of his views. Prof. Hennessy anticipated that the 

 discussion of observations in other islands would lead to their further confirma- 

 tion ; and it would ultimately follow, that not only are isothermals sinuous in their 

 shapes and not generally parallel to the equator, but that many would be found 

 which do not at all circumscribe the axis which joins the opposite poles of the earth. 



On an Instrument for observing [Vertical Currents in the Atmosphere. 

 By Professor Hennesst. 

 The author said he had been led to devise this instrument when offering an 

 explanation, printed in the ' Proceedings of the Royal Irish Academy,' of certain 

 abnormal phienomena sometimes observed on the surface of Lough Erne. The 

 instrument is constructed like a common wind-vane, but instead of the fixed tail, a 

 circular disc is placed vertically on an axis passing through the branches of a fork 

 at the tail end. This disc is pierced about half-way between its centre and circum- 

 ference so as to admit another axle, to the ends of which are firmly attached two 

 light rectangular discs. These discs are always in a horizontal position, whatever 

 may be the position of the circular disc, for each of them has ap endulum attached to its 

 centre by which the centre of gravity is kept considerably below the axle. These 

 discs, theiefore, cannot be acted on by a wind which blows horizontally. The position 

 of the circular disc will thus very clearly show whether any given current has an 

 upward or a downward tendency. The application of this instrument to the study 

 of mountain winds was pointed out, as well as to assist in studying some of the undula- 

 tory movements of the atmosphere. In the trials which have been already made 

 with it. Prof. Hennessy stated that it gave satisfactory results. The instrument is 

 of course not an anemometer, but simply a kind of universal anemoscope, for it shows 

 both the horizontal and vertical directions of a current. 



On Negretti and Zambra's Mercurial Minimum Thermometer. 

 By John Lee, LL.D., F.R.S. 



Dr. Lee exhibited the thermometer to the Section, and pointed out the advantages of 

 a thermometer of mercury in preference to alcohol, which is subject to unequal ex- 

 pansion at different degrees of heat ; it is a desideratum that ail thermometers in 

 a meteorological observatory should be constructed with one fluid, and that mercury, 

 the recognized standard measurer of heat. The thermometer has been tried at the 

 Observatory of Greenwich; by Mr. Glaisher, the Secretary of the British Meteoro- 

 logical Society ; Mr. E. J. Lowe of the Beeston Observatory, and several other emi- 

 nent meteorologists ; some instances have occurred in which errors in the alcohol 

 minimum thermometer have been corrected by the observations made by the mer- 

 curial minimum thermometer. 



Dr. Lee made some remarks upon a pamphlet recently printed by Dr. Herbert 

 Barker, of Bedford, on the relative value of the Ozonometers of Dr. Schcinbein and 

 Dr. Moffat, based upon daily observations made for eighteen months at Bedford, and 

 he drew the attention of the audience to the following points : — 1. Whether ozone 

 observations have generally been conducted by them in their meteorological ob- 

 servations? 2. Whether they use Schonbein's or Moffat's test papers, or both? 

 3. Whether they have noticed the difference between those which the Bedford 

 observations those of Mr. Glaisher in various parts of London, and those at Hart- 

 well House Observatory indicate ? 4. Whether they will without delay add the 

 Ozonometer to their instruments, as so much interest and importance belongs to 

 the mysterious agent. Ozone, which is carrying on its, at present, incomprehensible 

 effects' on the atmosphere, in order that they may be recorded r 



