269 



SCIENTIFIC SIDE-LIGHTS 



Forests 

 Forms 



similar principle, they plug up their older 

 channels, and then burst out in new ones; 

 nor is it uncommon to find among the cliffs 

 little hollow recesses, long since divested of 

 their waters by this process, that are still 

 thickly surrounded by coral-like incrusta- 

 tions of moss and lichens, grass and nettle- 

 stalks, and roofed with marble-like stalac- 

 tites. I am acquainted with at least one of 

 these springs of very considerable volume, 

 and dedicated of old to an obscure Roman 

 Catholic saint, whose name it still bears 

 (St. Bennet), which presents phenomena 

 not unworthy the attention of the young 

 geologist. It comes gushing from out the 

 ichthyolite bed, where the latter extends, in 

 the neighborhood of Cromarty, along the 

 shores of the Moray Frith; and after de- 

 positing in a stagnant morass an accumu- 

 lation of a grayish-colored and partially 

 consolidated travertin, escapes by two open- 

 ings to the shore, where it is absorbed 

 among the sand and gravel. A storm about 

 three years ago swept the beach several feet 

 beneath its ordinary level, and two little 

 moles of conglomerate and sandstone, the 

 work of the spring, were found to occupy 

 the two openings. Each had its fossils 

 comminuted sea-shells and stalks of hard- 

 ened moss; and in one of the moles I found 

 embedded a few of the vertebral joints of a 

 sheep. It was a recent formation on a small 

 scale, bound together by a calcareous cement 

 furnished by the fish-beds of the inferior 

 Old Red Sandstone, and composed of sand 

 and pebbles, mostly from the granitic gneiss 

 of the neighboring hill, and organisms, vege- 

 table and animal, from both the land and 

 the sea. MILLER Old Red Sandstone, ch. 10, 

 p. 184. (G. &L., 1851.) 



1312. FORMATION OF SCIENTIFIC 



THEORIES Mind Demands a Cause. Scien- 

 tific theories, in the first place, take their 

 rise in the desire of the mind to penetrate 

 to the sources of phenomena. From its in- 

 finitesimal beginnings, in ages long past, 

 this desire has grown and strengthened into 

 an imperious demand of man's intellectual 

 nature. It long ago prompted Caesar to say 

 that he would exchange his victories for a 

 glimpse of the sources of the Nile; it 

 wrought itself into the atomic theories of 

 Lucretius; it impels Darwin to those dar- 

 ing speculations which of late years have so 

 agitated the public mind. But in no case 

 in framing theories does the imagination 

 create its materials. It expands, dimin- 

 ishes, molds, and refines, as the case may be, 

 materials derived from the world of fact and 

 observation. TYNDALL Lectures on Light, 

 lect. 3, p. 95. (A., 1898.) 



1313. FORMATION OF WATER FROM 



GAS Mechanics of Explosion Speed of 

 Sound. Let us fill a soap-bubble with oxy- 

 gen and hydrogen gases in the proportion of 

 two parts of hydrogen to one of oxygen. If 

 we ignite it the result will be an explosion. 

 When the ignition takes place there is a 



sudden generation of heat, which suddenly 

 expands the air, causing it to be highly rare- 

 fied at the point of explosion. The air im- 

 mediately surrounding it is driven violently 

 outward in every direction. The first layer 

 of air-particles, surrounding the bubble, is 

 driven against the second, and then swings 

 back to its place, for the force that drove 

 it outward is no longer present. The second 

 layer swings against the third, and the third 

 against the fourth, and so on; each layer 

 after making its excursion outward returns 

 to its original position. The air-particles 

 are not fired at the ear as from a gun ; they 

 simply vibrate to and fro. The sound-pulse 

 moves outward like an expanding globe at 

 the rate of about 1,100 feet per second in 

 air, the speed depending upon the medium 

 through which it travels. ELISHA GRAY 

 Nature's Miracles, vol. ii, ch. 6, p. 59. (F. 

 H. & H., 1900.) 



1314. FORMS OF LIFE LOST AND 

 REINTRODUCED Remains of Extinct Race 

 of Horses in South America. In the pam- 

 pean deposit at the Bajada [Entre Rios, 

 South America] I found . . . [with re- 

 mains of the mastodon, etc.] also one tooth 

 of a horse, in the same stained and decayed 

 state. This latter tooth greatly interested 

 me, and I took scrupulous care in ascertain- 

 ing that it had been embedded contempo- 

 raneously with the other remains; for I 

 was not then aware that amongst the fossils 

 from Bahia Blanca there was a horse's tooth 

 hidden in the matrix: nor was it then 

 known with certainty that the remains of 

 horses are common in North America. Mr. 

 Lyell has lately brought from the United 

 States a tooth of a horse; and it is an in- 

 teresting, fact that Professor Owen could 

 find in no species, either fossil or recent, a 

 slight but peculiar curvature characterizing 

 it, until he thought of comparing it with 

 my specimen found here: he has named this 

 American horse Equus curvidens. There is 

 good evidence against any horse living in 

 America at the time of Columbus. Certainly 

 it is a marvelous fact in the history of the 

 mammalia, that in South America a native 

 horse should have lived and disappeared, to 

 be succeeded in after-ages by the countless 

 herds descended from the few introduced 

 with the Spanish colonists! DARWIN Nat- 

 uralist's Voyage around the World, ch. 7, p. 

 130. (A., 1898.) 



1315. FORMS OF LIFE, SEEMINGLY 

 INDEPENDENT, IN THE BLOOD White 

 Cells {Leucocytes} Battling with Germs of 

 Disease. We possess in our blood millions 

 of little living bodies, which are, in a sense, 

 independent of us autonomous subjects, as 

 it were, of the body at large. They are not 

 under our control in any sense, but live and 

 move, and discharge their duties as freely 

 as if they recognized no right or title of 

 their possessor to question their acts. . . . 

 Watching one of these living particles on a 

 miscroscope slide especially kept at the 



