44 REPORT — 1860. 



thus estimated has been applied, and all returns suspected of being erroneous 

 rejected. 



On the Similarity of the Lunar Curves of Minimum Temperature at Green- 

 tvich and Utrecht in the Year 1859. By J. Park Harrison, M.A. 



The author showed that, on the mean of twelve lunations, in 1859 the greatest 

 amount of cold displayed itself at both the above-named stations between full and 

 new moon : the difference between the mean minimum temperatures of the first and 

 second halves of the lunation at Greenwich being 2 0- 4 ; at Utrecht 2°"0. There were 

 two minima for night temperature both at Greenwich and Utrecht ; they followed on 

 full moon and last quarter. The least amount of cold was at first quarter. The 

 difference between the minimum temperatures at first quarter and shortly after last 

 quarter, on a mean of twelve observations taken at both stations, was nearly 7°. The 

 difference in the means of the mean temperature of the day for forty-three years for 

 the two periods of fourteen days, at the former place had been previously found to 

 be l°-l. 



Mr. Harrison expressed increased conviction that effects so contrary to expectation 

 must be due to the presence or absence of cloud, or to its height above the earth, — 

 to whatever cause this phenomenon may ultimately be assigned. 



On the Principles of Meteorology. By Professor Hennessy, F.R.S. 

 The author contended that the principal object of meteorology was the prediction of 

 the weather within certain probable limits. The great complication of atmospherical 

 phenomena, and the influence of remote causes of disturbance, would undoubtedly 

 render this extremely difficult. Although the atmosphere is itself one of the best 

 examples of an unorganized body to which we could refer, yet its complicated and 

 fluctuating phenomena suggest to us the mode in which such phenomena should be 

 investigated. Any success could be expected only by treating the atmosphere very 

 nearly as an organized body, and studying its abnormal conditions with the same 

 continuity and generality of observation as is usually employed in physiology. Ob- 

 servations made at stated hours have been found by themselves rarely capable of 

 affording means to foretell the future conditions of the weather for even short 

 periods of time. A careful study of the appearances of the sky, such as has been 

 so long familiar to mariners and others interested in the conditions of our atmo- 

 sphere, would, when made by men well prepared with preliminary knowledge of 

 the principles of physical science, throw far more light upon the chief object of our 

 search. Mr. Hennessy illustrated this remark by referring to some such observations 

 ■which he had made during the month of June. Although he had at first consi- 

 derable scepticism as to the possibility of obtaining correct results from the continuous 

 photographical registration of atmospherical conditions, Mr. Hennessy was satisfied, 

 from what he had witnessed during 1856 in the Radcliffe Observatory, that such a 

 system was not only possible, but that it sometimes disclosed important changes 

 which would have escaped the method of observation at stated hours. He instanced 

 the connexion between the phenomena of thunder-storms and sudden barometric 

 depressions, as pointed out by the late Radcliffe Observer at the Glasgow Meeting, 

 and the connexion between days of great solar irradiation and minute vertical 

 atmospheric currents, as pointed out by himself*. He concluded by pointing out 

 the manner in which, from the increasing knowledge we possess of the influence of 

 the ocean upon climate, the greater stability of its currents, compared to those of the 

 atmosphere, may under the peculiar conditions of the British islands enable us to 

 foresee many important changes within comparatively extended periods of timet. 



On Antarctic Expeditions. By Captain Maury, U.S. Navy. 



Observatory, Washington, 20th May, 1860. 

 My dear Lord Wrottesley, — I hope the time is not far distant when circum- 

 stances will be more auspicious than at present they seem ; for, as soon as there appears 



* Report for 1858, Trans. Sect. p. 36. 



t Report for 1859, Trans. Sect. p. 50. Proceedings of the Royal Society, vol. ix. p. 324. 

 Atlantis, vol. i. p. 396. Philosophical Magazine, April 1846, and October 1858. 



