TRANSACTIONS OF THE SECTIONS. 41 



one on record. Here again it is interesting to find the independent observations of 

 the writer, at the Hartwell Observatory, and of M. Goldschmidt at Paris, blending 

 so smoothly together — to form the light-curve. And I may here remark upon the 

 advantage of free intercourse in science. But for the valuable communications of 

 my two fiiends, I could only tell half my tale, and the curious failure of its appear- 

 ance in May 1858 would have remained "not proven!" Its truant nature is 

 well shown by the circumstance, that out of 162 nights on which it has been sought 

 for, it has been seen only on twenty-seven, and these distributed amongst four 

 observers. 



The details of the observations of these five stars, as well as of eight others, which 

 have in fact been the recreations of my leisure hours for some years past, after the 

 discharge of official duties at the Radcliffe Observatory, were to have been published 

 as a supplement to one of the future volumes of the Transactions of that establish- 

 ment, in which they were mostly made. The untimely death of my venerated Di- 

 rector and friend, M. J. Johnson, Esq., has interrupted this arrangement. 



As the various maxima and minima depend upon very different numbers of obser- 

 vations, a systematic and just assignment of the weight or comparative value of each 

 resulting equation has been duly regarded, and is an indispensable consideration in 

 all such investigations. 



It is singular how many of the variable stars have faint companions, though whe- 

 ther physically or merely optically double, years of accurate measurement can alone 

 distinguish. 



The empirical prediction of future changes, by the deduced epochs and periods, is 

 the first fruit, and perhaps for some time, the only yield to be expected from this 

 field of sidereal research. These are, however, so much wanted, that with the ap- 

 proval of my patron. Dr. Lee, and our distinguished neighbour Admiral W. H. Smyth, 

 to whose invaluable experience and ever readily bestowed counsel and encouragement 

 I owe the most grateful acknowledgments, the variable stars form the chief pursuit 

 towards which the resources of the Hartwell Observatory are directed ; and an Atlas 

 of the vicinity of every known variable, together with the determination of the 

 standard magnitudes of the most suitable comparison stars in their immediate neigh- 

 bourhood, is in an advanced state of preparation ; so as to relieve amateurs who are 

 inclined to take charge of a few of these interesting and amusing objects, of the only 

 tedious part of the process. Many possessors of small but good telescopes ex- 

 claim in despair, " What can I do to be useful with my small optical means, which 

 is not better done elsewhere ? " To such I would reply, " Record the changes of 

 some yet undetermined variable star !" It is little gain for all to be occupied on 

 the same objects, because they appear most striking and interesting ; plenty yet re- 

 main, the elements of variation of which are still unknown ; and to supply the first 

 good deductions of this kind ought to satisfy the ambition of any one who seeks to 

 be useful, without incurring the outlay of money, time, and trouble requisite for 

 the pursuit of the more advanced branches of the science. 



On the Effects of the Earth's Rotation on Atmospheric Movements. 

 By Daniel Vaughan, United States. 



Though much attention has been hitherto devoted to the motive power concerned 

 in producing the winds, there is still much room for investigations respecting the cir- 

 cumstances which modify its action. From the influence of heat in expanding the 

 air, and the manner in which temperature varies with an increase of latitude, it has 

 been inferred that the lower atmosphere must flow towards the equator, from remote 

 parts of the northern and southern hemisphere, while returning currents roll back 

 above the region of the clouds. On tracing the change which the earth's motion must 

 occasion on such moving masses of air, a very plausible explanation is obtained of 

 the leading phenomena of the trade-winds. But it seems difficult to account for the 

 geographical range of these regular movements of the air ; as their extreme limits, 

 even in the Pacific Ocean, extend only a few degrees beyond the tropics, and alter 

 position comparatively little during the different seasons of the year. The difficulty 

 appears greater, when we reflect that, in the torrid zone, temperature is not much. 



