210 



KNOWLEDGE 



[September 1, 1896. 



to fifty miles or more in diameter. A bird's-eye view of 

 one of these atolls from the masthead of a ship ia very 

 singular, giving the impression of a circular or oval fringe 

 of vegetation almost on the surface of the ocean. The 

 number of species of plants inhabiting these islands varies 

 from half a dozen to five and twenty, usually representing 

 nearly as many dilTerent genera and natural orders as 

 there are species. In some instances the vegetation con- 

 sists of scattered individuals of herbaceous plants and low 

 bushes ; in others of dense thickets, and even forests of 

 trees of considerable size. The coconut palm is usually 

 the most abundant and most conspicuous feature ; but how 

 far it owes its presence to human agency is uncertain. 

 There is no doubt that the fruit, like that of almost all 

 the plants associated with it, will bear long immersion in 

 sea-water without injury to the seeds, and seeds that are 

 cast ashore by unusually high seas germinate and grow. 

 It is also known that the Polynesians when visiting unin- 

 habited islands sometimes plant coconut and other seeds. 

 I'robably more has been done in this way to spread this 

 useful palm than is generally supposed. Common among 

 the herbaceous plants are a convolvulus, one or two kinds 

 of purslane, and in Polynesia a kind of cress. Screw 

 pines abound in some of the islands ; and other trees 

 occasionally occur up to fifty feet in height, with a trunk 

 as much as four feet in diameter. 



The natives of these islands subsist almost entirely on 

 coconuts and fish, the latter being extremely abundant in 

 the lagoons. 



EMERY. 



By EicHARD Beynon. 



WITH the ordinary uses of emery everyone is 

 familiar. From time immemorial this valuable 

 mineral product has been used in burnishing 

 metals and polishing stones, while during more 

 recent times it has become an essential factor 

 in the machinery of the steel worker or user. Few, 

 however, of those who are thoroughly familiar with the 

 emery paper or the emery hone of everyday life are aware 

 of the interesting story embodied in this useful substance. 

 The emery of commerce is neither more nor less than 

 an impure form of the mineral corundum. This latter 

 product contains, or should contain, little else than 

 alumina — aluminium and oxygen — and the value of emery 

 depends upon the nearness of its approach to pure alumina. 

 Ordinarily emery contains about seventy or seventy-five 

 per cent, of alumina, the chief remaining constituent, so 

 largely accountable for the dark or reddish-brown colour 

 of emery, being iron oxide. 



Emery does not appear to be what may be termed a 

 common mineral, though its geographical range is very 

 extensive. But whether occurrent in ice-bound Greenland, 

 the United States, the Spanish or Scandinavian peninsulas, 

 or the more classic regions of the Eastern Mediterranean 

 or Asia Minor, it is always found in amorphous masses, 

 usually detached blocks associated with gneiss, granular 

 limestone, or other crystalline rocks. 



So hard a mineral as is emery can only be quarried with 

 considerable difficulty, and though this is the case the 

 methods employed in the principal European source of 

 emery — Naxos, in the kingdom of Greece — are of the most 

 primitive character imaginable. The mineral is there 

 found in conjunction with hard limestones, and has in 

 great part been forced to or near the surface by igneous 

 upheavals, while aerial and other denuding forces have 

 further assisted in placing large quantities of emery within 



easy reach of the miners or quarrymen. It is, perhaps, 

 only by a stretch of courtesy that these emery operators 

 can be designated miners or quarrymen, so little is the 

 skill which they show in working the mineral. When 

 a block of emery is discovered, it has to be broken 

 into small portions so as to admit of easier transit 

 to the coast. The means employed to effect this 

 breakage are exceedingly crude and simple, but at 

 the same time not lacking in ingenuity. Fires are 

 lighted round the block so as to materially increase any 

 natural fractures or cracks which the stone may show. 

 Steel levers and wedges are then employed, and in this 

 way the most refractory blocks are reduced to sizeable 

 fragments, which admit of being carried on the backs of 

 mules to the port of debarkation. Inferior, however, as the 

 appliances and plant of these Greek quarrymen may be, 

 the labourers themselves are not without a certain measure 

 of skill in dealing with the emery. The quarries are 

 nominally worked by lessees, who indemnify the Govern- 

 ment for the right of exploiting the mines. The quarrymen 

 do not brook importations of non-local labour, their sons 

 succeeding them as labourers at the mines when sufficiently 

 old for the work. There is thus a certain traditional lore 

 extant at the mines, which is looked upon by its possessors 

 as a sort of professional secret and jealously guarded as 

 such. The miners are paid by the lessees according to 

 the output — in fact, they sell the emery to the nominal 

 owners of the mines. 



While such primitive methods are employed, it goes 

 without saying that the mines of Naxos are capable of 

 much more effective exploitation. As the surface supply 

 is practically exhausted, it is necessary, of course, to sink 

 shafts in order to reach the mineral, and the debris thus 

 excavated is simply dumped on the adjacent bank. Thus 

 it frequently happens that to reach further supplies these 

 heaps have to be subsequently removed, a proceeding 

 necessitating much labour and cost. 



In days gone by, when Naxos emery enjoyed a monopoly, 

 such unscientific methods of working did not matter much. 

 Now, however, the inferior emery found in the vicinity of 

 Smyrna is rapidly pushing it from the market. In fact, 

 were not the quality of the emery of Naxos guaranteed by 

 the Greek Government, and none but the beat quality 

 allowed to be exported, the emery of Naxos would ere 

 this have disappeared from the markets of the world. In 

 1818 it commanded over M'dO per ton, a price which has 

 now sunk to about one-twelfth of that amount. These 

 prices are those for the port of shipment only, the Loudon 

 merchant charging ici per ton or thereabouts, according 

 to quality. At present Naxos exports something like four 

 thousand tons per annum. It is shipped like coals, and on 

 arrival at the English or other manufactory is broken, 

 pulverized with stamps, sifted, and then by special processes 

 made into the hones, emery wheels, emery paper, and such 

 things, so necessary to the cutter and glass polisher. Such 

 in brief are some of the more interesting facts relative to 

 emery. 



♦ 



A CROCODILE MUMMY IN THE BRITISH 

 MUSEUM. 



By H. Spencer. 



UNDERGROUND Egypt is continually furnishing 

 us with new light on the religion, manners, and 

 customs of the people who lived in the land of 

 the Pharaohs long before the time of Moses. 

 The discovery of the Rosetta Stone in 1801 

 gave fresh impetus to the study of the language known as 



