April 12, 1894] 



NA TURE 



567 



adoption of such measures would be. As soon as a sanitary 

 measure has been approved anywhere, as soon as some hygienic 

 discovery has l>een made in the workshops of medical science, it 

 should be the duty of the S ate to try it, to estimaie its practical 

 value, and to make it generally known. 



It is only by such means that hygiene will become a science, 

 that this science will become the most important part of states- 

 manship, and that the Slate will become, as it ought to, a 

 healthy Stale. 



ACROSS CENTRAL ASIA. 



A T the meeting of the Ro)al Geographical Society, on April 

 -'*■ 9, Mr. St. George Liuledale read a paper on his recent 

 journey across Central Asia. Mr. and Mrs. Littledale left 

 England in January 1893, wiih the intention of crossing Asia 

 from wesi to ea-t, filling up >ome blanks in the map, and pro- 

 curing specmiens of the wild camel. After purchasing nearly 

 tv\o pony-loads of silver Yamboos, known on the Chinese coast 

 as Sycee Silver, they travelled in carts to Kurla, where they 

 organized a caravan of t' enty ponies and f rty donkeys, and 

 follow ed ihe river 'I'arim to Lob Nur. They camped by the 

 Lob Nor svvamp, but found the water too salt near the edge to 

 drink ; by wading out some distance they were ab'e to get some 

 less brackish, which was ju i drinkable. Along the Altyn Tag 

 range, a-^ far as the Galechan Bulak, there was a certain amount 

 of water and grazing. This was the point where the great 

 Russian traveller, Prjevalsky, turned back ; but beyond, the 

 desert was of an appalling nature — hardly any grass was to be 

 found, and water was very scarce ; all the men ^uffered greatly 

 fiom thirst, the animals 1 jsi flesh rapidly, and many died. Water 

 as a rule was only found every second day. Mr. Liuledale in 

 thi j district s lot four wild camels, one of which he has presented 

 to the British Museum. Prjevalsky's wild horse was not seen. 

 The guides were thorough scoundrels, and tried to wreck the 

 expedition in everyway ; on one occasion they denied the exist- 

 ence of a spring from which they were discovered getting water 

 sec etly during the night. 



Mr. Littledale was unable to see any trace of a large range 

 of inouniains marked on the maps as running north-east from 

 the Altyn i ag. When a few days' journey from Sai-ju they 

 met the first inhabitants, and in vain tried by bribes to get a 

 guide lo show a pass over the mountains. They afterwards 

 discovered that their interpreter was plajing false; he was 

 scheming to get 1 1 some town where he c uld desert. 



1 hey passed an embinkment several miles in length, w hich it 

 was diflicult to account for unless it was a contmua'ion of the 

 Great Wall of China from Suchan, two hundred miles to the 

 east. At Sai-ju the Chinese officials were civil, but trie I to 

 prevent the travellers returning lo the mouniains, and their 

 men, exhausted wiih their journey, were now in addition terri- 

 fied at the tales they heard of the Tonguts, a Tibetan robber 

 tribe, antl refused at first to go on. 



Colonel Yule questioned the accuracy of Marco Polo's state- 

 ment that it was a month's journey from Lob Nor to Sai-ju ; but, 

 curiously enough, ii. took Mr. Littledale exactly thirty days to 

 travers"- the distance. As they travelled further east, and crossed 

 the Humboldt range, thev found the map which had been con- 

 structed from native evidence entirely wrong, and a considerable 

 readjustment is necessary in order to secure an approach to 

 accuracy. Tiiey ptssed large herds of yaks and thousands of 

 antelopes and wild asses. Guides were a great difficulty, and 

 the party were soon left to fin i their own way. At one place 

 upwards of a hundred mounted Tonguts, carrying lances at 

 least fourteen feet long, match-lock guns, and swords, came 

 past their camp. Their followers predict' d an immediate 

 attack. Two Ladakis were sent to parley with them ; one 

 expounded a repeating rifle with such marked effect that when 

 the other man proposed t ' explain the beauties of a revolver 

 they begged hi-rt to 1 ut it a-.ide; and any idea, if it ever 

 existed, of a tacking the camp died a natural death. 



Mr. Li:tledale found his own way over the mountains by a 

 pass, and reach'r^d the hearl waters of the Buhain Gol. They 

 travelled for six days tlnouL'h a luxuriant grass country, and 

 camped on the shores of Koko Nor. Thirteen days more 

 found them hI Lanchan, where they disbanded their caravan ; 

 their interpreter, who was an anant coward, absolutely refusing 

 to go lo Pckin. Here some China inland missionaries kindly 

 helped them to ai range a raff, on which they drifted down the 



NO, 1276, VOL. 49] 



Hoang-ho, a journey of exceptional interest through country 

 which is largely un-mapped. Soon after leaving Lanchan the 

 river dashes through a narrow gorge, and the raft had several 

 narrow escapes of being broken up ; it was knocked out of 

 shape, and some of the logs smashed. The boatmen had each 

 an inflated sheepskin to act as a life-buoy in case of accident, 

 but none were provided for the passengers. Lower down the 

 river became broader and shallower, and they changed their raft 

 for a fl t-bottomed scow, and leached Bonto in twenty-five 

 days. From Bonto to the G eat Wall they passed through a 

 country abounding in ruined towns and villages, the result of 

 the disastrous Mahommedan rebellion in 1S61. On September 

 27 ihey passed through the Great Wall, and reached Pel<.in 

 three days later. 



ELECTRIC TRACTION. 



TN the present state of electrical science and practice, electric 

 ■^ traction must be considered as a branch of the ele;trical 

 transmission of energy. We require, first of all, a natural 

 source of energy, such as coal or other fuel, or water at a 

 high elevation or in motion. In the next place, we require a 

 prime mover to transform energy into work, such as a steam or 

 gas engine, a turbine, or water- or tide-wheel. Then this work 

 ha? to be iransfo.-med into eleotric current, by means of a 

 dynamo or magneto-electric machine, the so-called primary 

 machine. The electric current has then to be transmitted from 

 the place where it is produced to the place where it has to be 

 used, by means of a conductor or a storage battery. The current 

 has next to be retran^formed into work, by means of a motor 

 cirried by or attached tj the vehicle which has to be moved. 

 This work has then to be mechanically transmiite 1 from the 

 motor to the axle of the wheel of the car which travels along the 

 line. 



In each of these transformations and transmissions a loss takes 

 place, reducing the original unit of energy to a less and less 

 fraction of itself. In the case of water, with a turbine as the 

 prime mover, we obtain 60 per cent, of the energy as work or 

 motive power, or an efficiency of '6. With a steam-en;iine, owing 

 to the coal having to break up water into steam, a proportion 

 only of the heat or expansive energy of which can be applied as 

 pressure to drive the piston, because of the impossibility of 

 o )taining, at least at present, a perfect vacuum, or, stated other- 

 wise, of getting the lower limit of temperature anywhere near 

 the absolute zero ; and again, owing to the loss occasioned by 

 transforjiing the mo'.ion of translation of the piston into rota- 

 tory motion, we have a much smaller efficiency than in the case 

 of a water-wheel. About one eighth only of the energy of the 

 coal is transformed in a steam engine into work to drive the axle, 

 or we have an efficiency of only 125. 



The efficiency of electrical machines is very high, as high as- 

 ■9 with primary machines or dynamos, and 75 with secondary- 

 machines or motors. The conductor, or its substitute a storage 

 battery, offers a resistance to the passage of the current, and 

 when the latter is used its weight is so much extra weight to be 

 carried by the car. 



All these considerations seem to lead to the conclusion that 

 before electric traction can be employed on a very large scale, 

 we must possess a means of producing the electricity on the 

 spot and at the time it has to be used, or, in other words, we 

 must possess a battery in which the energy of coal can be trans- 

 formed directly into electric current, so that we may do without 

 storage batteries in which to carry electric energy about, or 

 heavy copper conductors through which to convey it ati 

 modera'ely low tension from the spot where it is produced to 

 where it is used, or light aerial conductors through which to 

 convey it at high tension. 



How long we shall be without this, or how many minds are 

 engaged in the solution of this or some such problem, we know 

 not, but the moment it is solved, and solved doubtless il will 

 be, there will be such a transformation scene in the industrial 

 applications of electiicity as one can hardly conceive. It would 

 mean that for almost every purpose except those in which healing 

 is required, electricity would or could be used. An electric 

 light-producing battery in every house, quite independently of 

 any mains in the streets; an electric power producing battery, lo^ 

 carry us w hither we would on rails or on the street ; and in every 

 house, to put an end to all the evils attendant on crowded! 

 factories and workshops in crowded streets and towns; such 



