52 



♦ KNOWLEDGE 



[Nov. 18, 1881. 



Tho np|>nrntuR oiiiploycd fi)r tlio aorioa of cxperinipnts vms a 

 small apri);lit Simnoiifi miioliiiio, worked by n giis-ciiffinc. Tho 

 two rnrboiiH in tlio rcffiilntor Ininp wrrc rrspoctively 10 nml 12 

 milliini^troH incliniiictor, iind tlio lijfVit it |.roiincprt wiib cqniil to 1,100 

 rnndlcfi. Tlin lirat pliin tlint wiis trie<l was by pliu'iii;^ tho lamp 

 about 7 ft. aliovo n melon pit. and a roflcctor was arranjfcd to con- 

 rrntnilc all the b'Kht on tho snah. I'oIh of rapidly-crowing plantH 

 woro, in Kiicrossion, brouffht nndor this inlluonoo. Bomo exposed only 

 to tho electric li),'ht, some to tho sun alone, and some to tho siiu 

 and electric liurht altoniatoly. Tho latter made tho most rapid 

 progress, and were the best in colour. In the next experiment, tho 

 lamp was put inaido a grecnhnuse, ami as near the roof as possible. 

 Various plants were placed in pots on tho floor, at a variety of 

 distances, and the light waskept burning all night foronowoek. Tho 

 plants nearest to tho influence of tho lamp made tho most rapid pro- 

 gross, and tho foliage and plants were of a far brighter hue than if 

 thoy hod only had sunlight during tho day. As regards forcing fruit, 

 tho electric light seems verj' oliicacious. In ten days time some 

 strawberrj- ])lant9, which had been kept alleniatcly under the 

 influence of tho sun and light, had large, full-flavoured fruit, while 

 plants which had only been exposed to tho rays of the sun for a 

 similar period, had merely green berries on them. There is no doubt 

 that tho u.so of artiticial sunlight in horticulture will be of immense 

 advantage; but whether it can be used by market gardeners and 

 people supplying the London markets, entirely depends on the price 

 at which it can bo produced. The machine used by Dr. Siemens, 

 of 1, too candle-light, costs about fivopenco an hour to work, ex- 

 clusive of a man, but including the cost of carbons. Dr. Siemens 

 is of opinion, that a light ei|ual to 0,000 candlos would prove 

 to bo economical in working. This would have to be fixed 20 ft. 

 above the ground. For forcing early fruits and flowers for the 

 iiondon markets, this discovery, if not too expensive, will be in- 

 valuable, as tho rays may bo concentrated on a brick wall, and by 

 ibis means fruit may be rapidly ripened. At a lecture at tho Royal 

 Institution, given by Dr. Siemenii, the action of the dynamo-electric 

 light was tried on some tnlijis, and it had the effect of causing tho 

 small buds to expand to full-blown flowers in about twenty minutes. 

 Tlie electric machine will apparently soon be applied to puqioaes of 

 general utility, as it enables work on a heavy scale to be carried 

 out, and it is already employed for telegraph work, superseding the 

 voltaic battery. Should Dr. Siemens succeed in producing it in a 

 cheap form, it would bo largely adopted, without doubt, in horticul- 

 turo, as the advantages of being early in the market are well 

 ■known. It seems almost an undisputed fact, that plants subjected 

 to the influence of tho dynamo-electric light arrive at perfection in 

 rather loss than half the time they would have taken if left only 

 to the rays of the sun. 



A PLANET OUTSIDE NEPTUNE. 



RATIIKR more than lialf-a-century ago, astronomers were begin- 

 ning to suspect that outside the path of the planet Uranus 

 another planet must travel, whose attraction caused Uranna to 

 deviate somewhat from the motions which theory assigned to him. 

 We know how this idea eventually led to the discovery of Neptune. 

 From tho observed disturbance of Uranus, the place of tho disturb- 

 ing body was determined by Loverrier and Adams independently, 

 and when the telescope was turned to the region of the heavens 

 where this as yet unknown planet should be, there, quite close to 

 the calculated spot, was his disc seen. It seems not unlikely 

 that before many years pass another planet further away than 

 JJcptune will be discovered. When Profes.sor Newcomb, of Wash- 

 ington, published his " Tables of Neptune " in 186G, he said, " It is 

 almost vain to hopo for the detection of an extra-Neptunian planet 

 from tho motions of Neptune before the close of the iiresent 

 century." But since Newcomb's " Tables of Uranus "were |)ul)- 

 lishod in 1S73 the jtlanet (Uranus) has been found to pass increasinglv 

 more in advance of its calculated place. Mr. I). P. Todd, Assistant 

 in tho Nautical Almanac Oilice at Washington, has found that by a 

 graphical method (the problem not being yet in such a condition 

 that proces.ses of calculation can be applied), that the position of a 

 disturbing body outside the orbit of Neptnne can bo approximately 

 interred. lie places this body at a distance from the sun exceeding 

 tho earth's (iftytwo times, so that its revolution around the sun 

 would require 373 years. Its present i)Osition along (or near) the 

 ecliptic would be within ten degrees either way of longituto 170°, 

 so that it might bo looked for ten degrees along the ecliptic, on either 

 side of tho starTnu Leonis. A.ssuming tho distance correctly taken 

 (as in the case of Neptune, the real planet may be at a much greater or 

 at a much less distance than the hypothetical one, without greatly 

 affecting tho result as to the di.-tturbing body's apparent position), 

 tho mass would be such that, assuming the density similar to that 



of the four giant planets, the apparent diameter would be abi.:.; 

 2"! (say about the {WWth part of the moon's), and it would npiienr 

 as a telescopic star of about the thirteenth magnitude. Ue puts 

 the point where the planet's path crosses the ecliptic in longitude 

 103°, and the inclination to the ecliptic as 1*21'. By the kindnesg 

 of Kear-Admiral Kodgers, supcrintondont of tho Washingttjn 

 Observatory, Mr. Toild wag allowed to begin the search for the 

 trans-Neptunian with the magnificent 2G-inch telescojw. A power 

 of '100 was employed, which would make the diameter eqaal to 

 nearly half the moon's, and shonld therefore show the disc verj- 

 obviously. On thirty clear moonless nights Mr. Todd searched 

 along tho neighbourhood of the ecliptic from longitude 

 120° 8' to longitude 180° 1', without learing any nnsearched 

 space between these longitudes. lie says, " if a trans-Neptunian 

 planet is ever discovered, having a diameter as great as 2", I shall 

 be very much surprised if it ia found that it must have eluded my 

 search." But he suggests that at and about the time of the 

 next opposition (which, if his assumed position is correct, would 

 occur within ten or twelve days on either side of March 20), a new 

 search should be made, with a telescope of sufficient power. If a 

 careful and sufficient search near the indicated longitude should 

 prove unavailing, it would be necessary to extend the obscrration to 

 a limited zone, all round the heavens. It is not likely that the 

 inclination of any trans-Neptunian planet to the ecliptic would b<' 

 more than 2°, so that an ecliptical zone 4° wide would probably 

 suffice for sunev. 



Reports of Societies. — We have been requested to insert reports 

 of the meetings of various societies. But the papers read before 

 scicntiflc societies are, as a rule, unsuited to our columns, and we 

 prefer (for the present at any rate) to give our space, which is 

 limited, to matter not requiring translation before it can bo under- 

 stood by tho general reader. We shall be very glad to find spaco 

 for clear and simple accounts by tho authors of papers communi- 

 cated to societies, of the matter which they properly enough present 

 in technical terms to fellow workers. And when papers are of suffi- 

 cient interest, we shall present our readers with translation specially 

 drawn up for those pages. But reports of scientific societies as usually 

 prepared, that is condensed versions of statements too technical 

 even without condensation to be generally understood, would be 

 simply a waste of space in a journal expressly intended to be of 

 interest to tho general public. Moreover, a large amount of 

 matter communicated to learned societies has no interest (even 

 when explained) to other than experts. Our wish is not that all 

 such matter as is thought suitable for communication to scientific 

 societies should appear in these columns (by a sort of editorial 

 pitchforking), but that whatever is worth knowing outside those 

 societies may be sifted out and placed, when duly translated, 

 before our readers. The former course would be tho easier ami 

 the cheaper; the latter seems the more honest, as alone in accord- 

 ance with our programme. 



Indiabibber G.iTHERiXG IX COLUMBIA. — Au interesting account 

 is given of this process in a report just issued by the United States 

 Consul at Carthngona. When tho hunter has found a rubber tree, 

 he first clears away a space from tho roots, and then moves on in 

 search of others, returning to commence operations as soon as ho 

 has marked all the trees in vicinity. He first of all digs a hole in 

 the ground hard by, and then cuts in the tree a V-shaped incision, 

 with a machete, as high as he can reach. The milk is caught as it 

 exudes and flows into the hole. As soon as the flow from the cuts 

 has ceased, the tree is chopped down, and the tnink raised from 

 the ground by means of an improvised trestle. After placing largo 

 leaves to catch the sap, gashes are cut throughout tho entire length, 

 and the milk carefully collected. When it first exudes, tho sap is 

 of the whiteness and consistence of cream, but it turns black on 

 exposure to the air. When the hole is filled with nibber it is 

 coagulated by adding hard soap, or tho root of the mechvacan, 

 which have a most rapid action, and prevent the escape of the 

 water that is always jiresent in the fresh sap. When coagjilatod 

 sufficiently, the rubber is carried on the backs of the hunters by 

 bark thongs to the banks of the river and floated down on rafts. 

 The annual destruction of rubber trees in Columbia is very great, 

 and the industn- must soon disappear altogether, unless the Oovern- 

 ment puts in force a law that already exists, which compels tho 

 hunters to tap the trees without cutting them do\vn. If this law 

 were strictly carried out there would be a good opening for com- 

 mercial enterprise, for rubber trees will grow from eight to ten 

 inches in diameter in throe or four years from seed. The trees re- 

 quire but little attention, and begin to yield returns sooner than 

 any other. Those that yield the greatest amount of rubber flourisli 

 on the banks of the Simu and Aslato rivora. The valuo of t! i' 

 whole indiarubber imported into the States annually is ab > ;t 

 ?10,000,000. 



