128 



KNOWLEDGE, 



[June 1, 1898. 



what is known in commerce as " pipe gamboge," which is 

 the best and purest quality, the second quality being 

 that which is collected in lumps. In Ceylon gamboge is 

 collectcci either from incisions made in the bark or by 

 cutting out pieces of it, from which the yellow juice oozes 

 and hardens on exposure, and the lumps are then scraped 

 off. Gamboge possesses powerfully purgative properties, 

 and was at one time used in medicine. At the present time 

 it is only used in veterinary practice. Its chief use, how- 

 ever, is as an ingredient for lacquering brasswork and as 

 a pigment in water-colour drawing. The well-known man- 

 gosteen is the fruit of a (ianinia — (i . mamjostana. It is a 

 moderate-sized tree of Malacca and the JIalay Archipelago, 

 but it has been introduced into other tropical countries. 

 It is the juicy pulp surrounding the seeds which is the 

 delicious morsel that has caused the mangosteen to be 

 classed as the best of all tropical fruits. 



Many other plants of this order might be mentioned as 

 yielding important economic products, but space will not 

 permit us to do so. 



TEEN^iTElEMIAcE.«. — This IS an order of trees and shrubs 

 chiefly tropical. It is not marked by any character- 

 istic property. In some of the South American species 

 the trees are noted for their hard and heavy woods and 

 the sweetness of the seeds, or nuts, as they are called, 

 the Souari nut of our shops (Caryocarmiciferum) being one 

 of them. The most important plant in the order — indeed, 

 one of the most important in the whole vegetable kingdom — 

 is the tea plant (Camellia tlna). From its early and very 

 extensive cultivation in China it was for a long time 

 supposed to have been a native of that country. It has, 

 however, been more recently shown to have originated 

 in Upper Assam, and to have been introduced to China at 

 a very early period. In like manner it was supposed for a 

 very long time that the black and green teas of commerce 

 were the produce of distinct species. This has likewise 

 been shown to be a fallacy, and it is now well known that 

 black and green teas are prepared from the same plant 

 by different methods of drying and curing. Thus, for 

 green tea, the leaves after gathering are not allowed to 

 lie so long as those intended for black tea before they 

 are rolled and roasted. By this means the fermentation 

 during the process of withering is avoided, and the leaves 

 in consequence retain much of their natural green colour. 

 Many details, which cannot be explained here, also have 

 to be followed, resulting in the two commercial kinds of 

 tea— black and green. In connection with the increased 

 demand for tea the world over, it will be interesting to 

 note that to meet that demand the range of the culti- 

 vation of the plant has considerably extended in recent 

 years. Thus we find it thoroughly established in Ceylon, 

 while in Japan, Java, and in Natal, excellent tea is grown 

 and prepared. 



The following figures will give an idea of the proportions 

 of the commerce in tea so far as Great Britain is con- 

 cerned: — The total imports for the year 1897 amounted to 

 two hundred and sixty-nine million, thirteen thousand, four 

 hundred and eighty-two pounds, of the value of ten million, 

 four hundred and forty-three thousand, one hundred and 

 four pounds. 



DiPTERocARPE.E. — The plants composing this order are 

 for the most part large forest trees of India, noted for the 

 strength and durability of their timber and for the valuable 

 resinous products they yield. The best known in the first 

 category is the sal or saul tree (Shorea rohusta), a tree 

 forming extensive forests over a wide range in India, where 

 the timber is almost, if not quite, of equal value as teak, 

 and is in great demand for gun carriages, raOway sleepers, 

 and building purposes generally. It, moreover, yields a 



quantity of resin known as " dammar," and used for pre- 

 serving the woodwork of boats. From several species of 

 Tlijileroiarpus, notably /'. aliitus, D. turhi}uitus, and Z>. 

 trinenis, an oleo-resin known as " wood oil," or " Gurjun 

 balsam," is obtained, chiefly from the coast of Burma and 

 the Straits of Malacca. To collect the balsam, the trees 

 are tapped at the end of the dry season by making several 

 deep incisions with an axe into the trunks and scooping 

 out a good-sized cavity. Fire is lighted in this hole, and 

 when the wood has become heated or scorched the balsam 

 begins to flow. After collection it is allowed to settle, 

 when the clear liquid or oil separates from the more solid 

 or resinous portion. It is said that as much as thirty or 

 forty gallons has been obtained from a single tree in one 

 season. Though it is used in India as a substitute for 

 balsam of copaiba, its chief use is as a natural varnish for 

 preserving woodwork from atmospheric effects or the 

 attacks of white ants. The Sumatra camphor tree (Dryo- 

 balanops aromatka) is of considerable interest in con- 

 sequence of its peculiar habit of forming masses of 

 camphor crystals in clefts of the trunks. It is much less 

 volatile than ordinary commercial camphor, and fetches a 

 high price amongst the Chinese, by whom nearly the whole 

 of the produce of Sumatra is taken, and these people 

 believe it to possess many remarkable properties. It 

 does not reach Europe, except occasionally as an article 

 of curiosity. 



The only other product of the I Hpterocarpene that space 

 will allow us to mention is that known as " piney resin," 

 or " Indian copal," the produce of Vuteria indica, a tree of 

 Malabar. This resin is of a semi-fossiUzed character, and 

 is used slightly in the preparation of varnish. From the 

 large fleshy seeds a kind of fat or tallow is obtained, which 

 is used in India for making candles, and is known as 

 " piney tallow." 



WEATHER ACCOUNTS. 



By Alex. B. MacDowall, m.a. 



AN analogy might be traced between the fluctuations 

 of weather and those of a banking account. And 

 we might deal with the plus and minus values of 

 the former (with reference to an average) as we 

 might with sums deposited in a bank and sums 

 withdrawn, so as to show the position of affairs at any 

 given date in relation to a previous date. 



Thus, suppose a man opens a banking account, which 

 he is allowed to overdraw. The first week he deposits 

 ten pounds and the next ten pounds. Next he draws five ; 

 then deposits ten ; then draws thirty. The final resuli 

 obviously is that he is five pounds " to the bad." And 

 this set of transactions, and the position each week, might 

 be simply represented thus : — 



1 2 3 4 .5 



Transactions ...10 -F 10 - 5 -I- 10 - 30 = - 

 State of Account ...10 -f 20 -i- 15 -h 25 - 5 



On the other hand, take as a simple case of weather 

 the monthly amounts of rain in London last year. Mr. 

 Symons, in his magazine, gives us the plus or minus 

 values in which these are referred to an average. We 

 proceed accordingly thus ; — 



Jan. Feb. Mar. April. 



+ -43 + -87 + 1-81 - -17, etc. 

 4- -43 -I- 1-80 -f 3-11 -I- 2-94, etc. 



The second line, completed, we may plot as a curve 

 (H, Fig. 3). 



We often hear questions like this, " Have we had more 



