TRANSACTIONS OF THE SECTIONS. 45 



On Naval Anemometrical Observations. By Professor C. Piazzi Smyth. 



After alluding to the mechanical importance of the trade-winds in the economy of 

 the atmosphere, the author pointed out the naturally admirable circumstances of a 

 station on the surface of the sea for making exact observations to this end ; but 

 indicated also the artificial difficulties that were opposed by the eddies caused about 

 the actual station, viz. the deck of a ship, as well as by its proper motion. From a 

 series of observations communicated to him by Captain H. Toynbee, the author had 

 concluded, that the only unexceptionable station for anemometrical observation at 

 sea was the mast head. Accordingly he exhibited a combined apparatus for the 

 direction and the velocity of the wind, arranged with a view to such a position, and 

 also with a view to accurately observing the mean effects, and this, by a summation 

 of every individual gust, even the lightest. For the most accurate plan of securing 

 data, he had arranged a method of electric registration which was extremely simple, 

 and proceeded in the cabins below while the anemometers were measuring the wind 

 aloft. 



Notices of Rain-falls for a Series of Years at Home and in Foreign Countries. 



By P. L. SiMMONDS. 



After pointing out the advantages which would result from an accumulation of facts 

 that would serve to guide us to a knowledge of the mean average fall of rain in cer- 

 tain periods, the proportionate evaporation, and. the alternation of wet and dry 

 seasons, Mr. Simmonds pointed out the value of such inquiries to the agriculturist, 

 the physician, and the statist ; and showed how important was this knowledge of the 

 mean annual fall of rain in particular localities, and the average number of days in 

 which rain fell in the year. Particular crops, as the sugar-cane, the indigo-plant, 

 the cotton- and tobacco-plants might be entirely ruined by too much or too little 

 rain. Many localities, such as Malta, Gibraltar, Ascension, &c., are obliged to hus- 

 band the rain-water in tanks. The navigation of rivers and the irrigation of adjacent 

 lands are also dependent on a certain amount of rain ; and the potato, the vine, and 

 other plants are injuriously affected by the condition of the atmosphere and the super- 

 abundance of moisture. Even the fact of whether the moon has any influence on 

 the fall of rain is still a disputed point. 



The relative proportions of rain that fall by night and by day was another point 

 touched on. Mr. Simmonds then took a survey of the records of this branch of 

 meteorology in the various quarters of the globe, citing the comparative falls of rain 

 in the tropics and in temperate regions in different countries. 



On Waterspouts. By Dr. Taylor, Professor of Natui'dl Philosophy, 

 Andersonian University, Glasgow. 



The author, after describing the phsenomena of the Waterspout, stated the different 

 theories which had been proposed as to their nature and origin, and showed that 

 the only one which, in the present state of science, is at all tenable, is that which 

 ascribes the descent of the cone of cloud and the ascent of water or other sub- 

 stances, to the partial vacuum created in a portion of the atmosphere by the action 

 of contending currents producing a whirlwind. He next pointed out the difficulties 

 encountered in applying this theory to the explanation of some of the phenomena, 

 such as the division of the " tube " into several portions towards its lower part, 

 which are often seen to twist about each other like coiling snakes, and also to present 

 the appearance of a dilation running up the tube like the action of the throat of an 

 animal in drinking. After showing, by calculation founded on the laws of dynamics, 

 that the rapidity of rotatory movement necessary to produce any considerable 

 approach to a total vacuum in the interior of the tube cannot possibly exist in any 

 case, it was proved that a shred of cloud, of slightly less specific gravity than that of 

 the atmosphere below it, might easily be made to descend by a comparatively slight 

 degree of rotatory rapidity ; and also that spray from the sea or light bodies from the 



