Page:Popular Science Monthly Volume 24.djvu/877

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swered. But the author was held up to ridicule, in a leading article in "Nature" of January 25, 1883, as the victim of "a thirst for scientific renown," who knew nothing of the subject concerning which he had given the result of his studies, but had succeeded in imposing himself upon a respectable scientific body, and upon a scientific journal. Mr. Whitehouse has taken his time to answer this attack, and has replied to it with vigor and to the point in a late number of the "Manhattan." Setting by the side of one another photographs of the Island of Staffa and Fingal's Cave, and the representations of them given in the current works on geology, he shows that a wonderful ignorance of what they are like exists in the scientific mind, and is transmitted to students. German works exhibit a structure supposed to have been exposed for millions of years to waves capable of hollowing out two hundred and twenty-eight feet of basalt, and open at both ends, which Fingal's Cave is not, compared with which "wall of bricks without mortar would be solidity itself." Hitchcock's "Geology" long gave a view that did not show any part of Staffa, but the adjoining Island of Boo-sha-la. Dr. A. Geikie, Director of the Geological Survey of Scotland, gave, in his "Primer" in 1881, "a tolerable engraving of part of the island"; but, in 1882, he offered to more advanced students, in his "Text-Book of Geology," "a problem in physics and drawing which has hitherto passed uncriticised," "the bad copy of a picture for which its author apologized in 1819," "which picture was no more Staffa than a view inside the railings at the head of Wall Street would be Trinity Church." If our young American has been too hasty in his theories, upon which we do not undertake to decide, it certainly behooves his critics, and especially those who are on the spot and wear official titles, to attempt some approach to accuracy in fact.

Why some Bodies feel colder than others.—It is a familiar fact that, when we touch with the fingers different substances of the same temperature, some will feel colder than others. The differences of the feeling are commonly ascribed to differences in the heat-conducting powers of the several bodies. A correspondent of "La Nature" suggests that, besides this, the specific heat of the bodies and the degree of polish of their surfaces should be taken into account. The effect of specific heat may be observed by pouring alcohol upon water and plunging the finger in so that a part of it shall be in the water and a part in the alcohol. The part in the water will feel much colder than that in the alcohol. So brandy may be taken, with safety, at a degree of cold at which water would infallibly irritate the skin. The effect of the degree of polish may be tried with a piece of marble or glass one side of which is smooth and another rough, with a file one side of which has been ground down, or with glazed and unglazed paper. In every case the smooth side or substance, at ordinary temperatures, will appear colder than the rough one. The fact may be accounted for by remembering that the smooth body presents vastly more points of contact with the fingers, and consequently more conductors for the heat than the rough one. In like manner a liquid always seems colder than the vessel containing it, because it is in closer contact with the skin.

Are there Birds with Teeth?—The "Transactions" of the Natural History Society of Leipsic contains a paper by Dr. Paul Fraisse, on teeth and tooth-papillæ in birds. It is generally admitted that there is a series of birds having real teeth in their bills. Among these are the fossil archæopteryx of Solenhofen, and the odontornithes, discovered by Professor Marsh in the North American cretaceous. The jaws of the latter birds were furnished with teeth, and also with cavities containing supplementary teeth, like those of crocodiles. The curious relations which these birds exhibit with reptiles, as a kind of transitional stage between the two orders, suggest the question whether any living birds have teeth. On this point, Dr. Fraisse remarks that Geoffroy Saint-Hilaire in 1821 discovered in two embryos of the parrot (Palæornis torquatus) papillæ which he regarded as tooth-sacs and as homologous with the rudimentary teeth of other animals. In one of the jaws there even seemed to be duplicate rudiments, as among the mammalia. Cuvier accepted this an-