30 



♦ KNOWLEDGE ♦ 



[July 11, 1884. 



needle, and two or three cells of, say, a bichromate battery. 

 First, float the needle on a glass of water by laying it on a 

 small piece of paper or cork. (If the baud and the needle 

 are dry, the film of air adherent to or surrounding the 

 needle will, generally speaking, prevent it from sinking.) 

 Then, holding the handle of the poker and one end of the 

 wire in the left hand, held out from the body, proceed to 

 wind the wiie over the other end of the poker with 

 the riglit hand, moving the hand continuously in the 

 same direction as that taken by the hands of a watch, as 

 seen when lookiig at its face. In other words, taking the 

 wire in the right hand, pas.s it from the upper side down 

 the right side across the bottom, and back up the left side. 

 In this way cover the square end of the poker with one 

 layer or thickness of wire. Such a coil of wire is called a 

 helix, and helices are divided into two class^es — called right- 

 handed and left-handed (according to the direction of wind- 

 ing). The helix just constructed and illustrated in Fig. 1 



(depicting an iron rod, X S, inside of a piece of 

 glass tubing, over which the wire is wound), is a 

 left-handed one — a current on entering it at either end 

 travelling through it in a direction opi osite to that of the 

 hands of a watch. To secure a right-handed helix (Fig. 2), 



^(2V^ 



Fig. 2. 



wind the wire round the ])oker from right to left, or move 

 the hand in the oppo.site direction to that of the watch 

 hands. The current in flowing through thi.s helix tr.avels 

 in the opposite direction to that taken in the other, and, 

 as we might anticipate, different causes produce different 

 effects. 



(To ie contimied.) 



THE ANTARCTIC REGIONS. 



By R. a. Proctor. 



(Continued from page 7.) 



IT is singular how confidently geographers have spoken 

 of the great Antarctic continent, when we remember 

 that only an inconsiderable extent of coast line has even 

 been seen by Anctarctic voyagers in any longitudes, except 

 where Ross made his nearest approach to the South Pole. 

 There is absolutely not a particle of evidence for believing 

 that the ice-barriers which have been encountered — Sabine 

 Land, Adelie Land, Victoria Land, and Graham Land — 

 belong to one and the same land region. It is not, indeed, 

 certain that all tlie mapped coast-line is correct — for it must 

 not be forgotten that where Commodore Wilkes charted 

 down a coast-line Ross found an open (or only ice-encum- 

 bered) sea, and sailed there. 



Yet Dr. Jilek, in the "Text-book of Oceanography," in 

 use in the Imperial Naval Academy of Vienna, writes thus 

 confidently respecting the Antarctic continent : — " There is 

 now no doubt," he says, " that around the South Pole there 

 is extended a great continent, mainly within the polar 

 circle, since, although we do not know it in its full extent, 

 yet the portions with which we have become acquainted, 

 and the investigations made, furnish sufficient evidence to 



infer the existence of such with certainty. This southera 

 or Antarctic continent advances farthest in a peninsula 

 S.S.E. of the southern end of Americu, reaching in Trinity 

 Land almost to 62 degrees south latitude. Outwardly these 

 lands exhibit a naked, rocky, partly volcanic desert, with 

 high rocks, destitute of vegetation, always covered with ice 

 and snow, and so surrounded with ice that it is difiicult or 

 impossible to examine the coast very closely." 



A singular, and indeed fallacious, argument has been 

 advanced by Captain JIaury in favour of the theory that 

 the Antarctic regions are occupied by a great continent. 

 " It seems to be a physical necessity," he argues, "that land- 

 should not be antipodal to land. Except a small portion 

 of South America and Asia, land is always opposite to 

 water. Mr. Gardner has called attention to the fact that 

 only one twenty-seventh part of the land is antipodal to 

 land. The belief is, that on the polar side of 70 degrees- 

 north we have mostly water, not land. This law of dis- 

 tribution, so far as it applies, is in favour of land in the 

 opposite zone." Surely a weaker argument has seldom 

 been advanced on any subject of scientific speculation. 

 Here is the syllogism : we have reason to believe (though 

 we are by no means sure) that the Arctic regions are 

 occupied by water ; land is very seldom found to be anti- 

 podal to land ; therefore, probably, the Antarctic regions 

 are occupied Viy land. But it is manifest that, apart from 

 the weakness of the first premiss, the second has do bearing 

 whatever on the subject at issue, if the jirst he admitted : 

 for we have no observed fact tending to show that water 

 is very seldom antipodal to water, which wouW be the 

 sole law to guide us in forming an opinion as to the 

 regions antipodal to the supposed Arctic water. On 

 the contrary, we know that water is very commonly 

 antipodal to water. We have only to combine what is 

 known respecting the relative ])roportions of land and 

 water on our globe with Mr. Gardner's statement that 

 twenty-six out of twenty-seven parts of the land are anti- 

 podal to water, to see that this must be so. There are about 

 .51 millions of square miles of land and about 146 millions 

 of square miles of ocean. Now about 49 millions of square 

 miles of land are antipodal to water, accounting therefore 

 for only 49 millions out of the 146 millions of square miles 

 of ocean surface ; the remaining 97 millions of square miles 

 of ocean are, therefore, not antipodal to land, but one half 

 (any we please) antipodal to the other half. In fast, we 

 have this rather singular result, that the ocean surface of 

 the globe can be divided into three nearly equal parts, of 

 which one is antipodal to land, while the other two parts 

 are antipodal to each other. This ob\"iously doe.s not force 

 upon us the conclusion that an unknown region must be 

 land because a known region opposite to it is oceanic ; and 

 still less can such a conclusion be insisted upon when the 

 region opposite the unknown one is itself unknown.* 



* Whether the relation above-meutioned respecting Xand regions- 

 is noteworthy may very well be questioned. It will be seen that 

 Captain Maury regards it as seemingly a physical lore " that land 

 should not be antipodal to land." Now this is by no means satis- 

 factorily indicated. As a question of probability it is not certain 

 that the present relation, by which twenty-six parts out of twenty- 

 seven of the land are antipodal to water, can be rej^rded as 

 antecedently an unlikely one, when nearly three-fourths of 

 the whole surface are occupied by water, and when, also, 

 the bulk of the land and water regions consist of such 

 great surfaces as those we call continents and oceans. Granted 

 these preliminary conditions, it would appear, indeed, that only 

 by a very remarkable and, as it were, artificial arrangrtnent of 

 land and water could any btit a small proportion of the land be 

 antipodal to land. The stress laid by JIanry on the observed rela- 

 tion seems to me, indeed, as unwarranted as that laid by Humboldt 

 on the fact that the great southerly projections of the land lie nearly 

 in the same longitude as the great northerly projectioms. 



