396 Quer-ies a?id Answers. 



freezing, and spreading into large sheets, which, from ice being lighter than 

 an equal bulk of water, are frequently torn up in large bodies, and floated 

 away with stones and gravel adhering to the under surfaces. Why ground 

 ice is not frozen in the same way at the bottoms of deep and still pools, 

 well merits a special notice. Water, on decreasing its temperature, in- 

 creases in density down to about 40°, which is its maximum density ; and 

 from that point it continues expanding up to freezing. The cooling pro- 

 cess always proceeds over the surface, and as the water there acquires 

 gravity, it descends, and is replaced by some warmer, and, of course, 

 lighter water, which, being at length cooled, sinks in its turn, and in like 

 manner the cooling process goes on, until the whole body of the water 

 attains the temperature of 40°. The cooling process still going on, the 

 surface water expands, and becomes specifically lighter than that below, 

 and is detained there until it freezes ; while the great body below, being 

 all at its maximum density, remains quiescent, and preserves its fluidity 

 through the longest and severest frosts, even in very high latitudes. This 

 simple and admirable provision in the constitution of water operates the 

 most important consequences in the wise economj' of nature : without it, 

 all ponds, lakes, and other deep and still bodies of water, would be frozen 

 into solid masses, and, of course, all their living productions destroyed. — 

 J. Carr. Alnwick, Jan. 8. 1832. 



Dew, — The annual average quantity deposited in this country is esti- 

 mated at a depth of about 5 in., being about one seventh of the mean 

 quantity of moisture supposed to be received from the atmosphere, over all 

 Great Britain, in the year ; or about 22,161,337,355 tons, taking the ton at 

 252 imperial gallons. (Literary Gazettey Jan. 29. 1831.) 



Spot on the Sun. — A dense smoke fog prevailed on the morning of the 

 25th of the tenth month (October), in the vicinity of the metropolis ; and 

 about 9 o'clock the sun became sufficiently visible for the naked eye 

 steadily to survey its disc, when a large spot was distinctly seen near its 

 centre. The mist must have possessed considerable magnifying power, as 

 the observer endeavoured in vain to discover the same spot some hours 

 after with the naked eye, protected by a single darkened glass. With one 

 of Dollond's 3 ft. telescopes, however, it vi^as perfectly visible, together 

 with another spot near the western limb. — B. Laytonstoney Aprily 1830. 



Art. II. Queries and Answers, 



List ofy and short critical Remarks on, the current Periodicals on Natural 

 History. — Sir, A. R. Y. would oblige me, and perhaps some of your other 

 correspondents, if he would give a list of the numerous periodicals now 

 published on the subject of natural history, stating which deserve encourage- 

 ment, &c. Perhaps his time would not be thrown away, as he must know 

 the wide circulation your Magazine has. — M. F. Jan. 12. 1832. 



Mr. Dovaston's Ornithoscope. (p. 83. and 205.) — Mr. Dovaston explains 

 (p. 380.) that this is but a small pocket telescope, so denominated when 

 applied to ornithic objects. — J.D. 



In twin-born Calves, is one of the two invariably sterile ? andy if the two be 

 Male and Female y is the sterile one invariably the Female ? — Sir, When on 

 a visit, some years ago, at a farm-house, the occupier of which had had 

 considerable experience in breeding cattle, I was told by him that when a 

 cow produced twin calves, of different sexes, the female was always sterile, 

 and that therefore he reared it only for the butcher. Whether the male had 

 the power of generating, I do not recollect if he stated. Can any of your 

 correspondents contradict or confirm this statement j or say whether this 

 curious law obtains with any other animal ? 



