if, 



uatment 

 vance 



SCIENTIFIC SIDE-LIGHTS 



16 



church-clock at a distance, I should have to 

 diminish the distance between the object- 

 glass and the eye-piece; and I cannot con- 

 ceive of any optical mechanism by which the 

 telescope could be enabled to make this ad- 

 justment for itself. That the eye should be 

 provided with such a mechanism has al- 

 ways seemed to me a most wonderful evi- 

 dence of intelligent design; and the im- 

 portance of this provision in our daily life 

 is so great (as every one knows in whom it 

 is even partially deficient) as to outweigh 

 beyond all comparison the slight want of 

 optical perfection which ... is insep- 

 arable from it. CARPENTER Nature and 

 Man, lect. 15, p. 425. 



78. ADVANCE ALONG ABORIGINAL 

 LINES Improvement in Mechanic Arts Per- 

 fected Snow-shoes. The Canadian Indians 

 and those of the northern United States, 

 having only soft material and bark to work 

 upon, restrict themselves mostly to the long- 

 bladed curved knife. On the Pacific coast, 

 among Indian tribes from Mount St. Elias 

 and southward, there is a mixture of hard 

 material and soft wood, so that there is a 

 great variety in the form of the whittler's 

 knife. Furthermore, these tribes have been 

 in contact with sailors for more than a cen- 

 tury, and use any piece of steel or iron they 

 can secure in trade. The Canadian Indians 

 were stimulated by the fur-trading com- 

 panies to travel more rapidly and to make 

 longer journeys ; hence, in furnishing them 

 with the curved knife, they made it possible 

 for these Indians to work out the frame of 

 the birch-bark canoe, the bows of the snow- 

 shoes, splints for basketry, and a thousand 

 and one objects made of birch-bark, with 

 this simple but most efficient device. It 

 has become the traveling tool of the Cana- 

 dian Indians and has done more than aught 

 else to improve their mechanical skill. An 

 examination of old patterns of snow- 

 shoes, in comparison with the latest pat- 

 terns, reveals an astonishing improvement. 

 The versatile curved knife is just as useful 

 in the making of fine babiche or rawhide 

 string for the webbing of the snow-shoe as 

 in whittling down the frame. In the old- 

 fashioned snow-shoes the rawhide footing is 

 nearly one-fourth inch wide, while in the 

 best and latest the strands are as fine as 

 thread. MASON The Man's Knife Among 

 the North American Indians, (Report of the 

 U. S. National Museum), p. 732. 



79. ADVANCE FROM KNOWN TO 

 UNKNOWN Acquaintance with Phenomena 

 of Sound-tea ves Led to Discovery of Waves 

 of Light Young Demonstrates the Undu- 

 latory Theory. In the year 1773 was born, 

 at Milverton, in Somersetshire, one of the 

 most remarkable men that England ever 

 produced. He [Thomas Young] was edu- 

 cated for the profession of a physician, but 

 was too' strong to be tied down to profes- 

 sional routine. He devoted himself to the 

 study of natural philosophy, and became in 



all its departments a master. He was also 

 a master of letters. Languages, ancient and 

 modern, were housed within his brain, and, 

 to use the words of his epitaph, " he first 

 penetrated the obscurity which had veiled 

 for ages the hieroglyphics of Egypt." It 

 fell to the lot of this man to discover facts 

 in optics which Newton's theory was incom- 

 petent to explain, and his mind roamed in 

 search of a sufficient theory. He had made 

 himself acquainted with all the phenomena 

 of wave-motion; with all the phenomena of 

 sound; working successfully in this domain 

 as an original discoverer. Thus informed 

 and disciplined, he was prepared to detect 

 any resemblance which might reveal itself 

 between the phenomena of light and those of 

 wave-motion. Such resemblances he did de- 

 tect; and, spurred on by the discovery, he 

 pursued his speculations and his experi- 

 ments until he finally succeeded in placing 

 on an immovable basis the undulatory the- 

 ory of light. TYNDALL Lectures on Light, 

 lect. 2, p. 50. (A., 1898.) 



8O. ADVANCE IN OUR KNOWLEDGE 

 OF LIVING ORGANISMS Inadequate Early 

 Estimates. The species known to the nat- 

 uralists of early times were few in number 

 at least, comparatively and the old 

 students had no idea of the excessive di- 

 versity of form and structure familiar to 

 us. A census of animals and plants was 

 taken by Ray [1670-93] shortly before Lin- 

 naeus commenced his career, and enumerated 

 less than 4,000 animals, exclusive of in- 

 sects; and of those it was estimated that 

 there were about "20,000 in the whole 

 world." He evidently believed that the en- 

 tire number living would not be found 

 greatly to exceed this. But let Ray speak 

 for himself. According to the author's clas- 

 sification, animals were divided into four 

 or( i ers "beasts, birds, fishes, and insects." 

 The number of beasts, including also ser- 

 pents, that had been accurately described, 

 he estimated at not above 150, adding that, 

 according to his belief, " not many that are 

 of any considerable bigness, in the known 

 regions of the world, have escaped the cog- 

 nizance of the curious." (At the present 

 day more than 7,000 species of "beasts," 

 reptiles, and amphibians have been de- 

 scribed. ) The number of birds " may be 

 near 500; and the number of fishes, exclu- 

 ding shell-fish, as many ; but, if the shell-fish 

 be taken in, more than six times the num- 

 ber." As to the species remaining undis- 

 covered, he supposed " the whole sum of 

 beasts and birds to exceed by a third part, 

 and fishes by one-half, those known." The 

 number of insects that is, of animals not 

 included in the above classes he estimated 

 at 2,000 in Britain alone, and 20,000 in the 

 whole world. . . . About 375,000 species 

 of animals are now known, and of insects 

 we still know the smaller portion. . . . 

 The late Dr. C. V. Riley even went so far as 

 to say " that there are' 10,000,000 species of 



