178 



NATURE 



\ytme 19, 1879 



III. 



The induction plate was lowered from 2 inches to \\ inch. Current — . (The current + was not observed 



for want of time.) 



Ring I 2 3 4 5 6 7 8 9 10 



Readings 276 217 200 187 174 159 144 130 116 104 



Differences . . . 



59 17 13 13 IS IS 14 14 



14 14 14 14 13 13 22 



The observation III. illustrates that which has already 

 been said concerning the fall of potential within the tube. 

 In case I. we have for the currents in webers — 



C + 



_ -f^v X 2400 X 1-03 



00007261, and 



i,ooo,oco 

 35^0^2400 x^3 ^ o.^g^g,^ 



1,000,000 



and for the difference of potential in volts ( V) between the 



two ends of the tube — 



(C +) K= \\\ X 2400 X i'03 = 1730, and 

 (C-) F=i^i X 2400 X 1-03 = 1618. 



These differences of potential would be reproduced if 

 for the tube were substituted metallic resistances in 

 ohms (/?) — 



(C +) ^ = Vt X 1,000,000 = 2,383,000, and 

 (C - ) A' = V/ X 1,000,000 = 1,954,000. 

 In case II. — 



c+ =: 



2400 X I'O^ , , 



-2 J = o 0003674, and 



800,000 

 X 2400 X 



I 03 



; 0'0004I90. 



X 2400 X i'03 = 1756, and 

 2400 X f03 = 1736. 



800,000 



(C-)F=f||> 



(C ■\-) R = t!^ X 8co,ooo = 4,780,000, and 



(C -) R — i5-i X 800,000 = 4, 142,000. 



Selecting the observations with the current positive in 

 each case and placing these in juxtaposition thus — 



c V R 



Case I. 0-0007261 ... 1730 ... 2,383,000 

 ,, II. O'ooo3674 ... 1756 ... 4,780,000 



we see that when C is varied in the ratio of 2 : i, F 

 remains sensibly constant, R varying as i : 2 ; that is to 

 say, though the current is halved, the difference of 

 potential between the ends of the tube remains constant 

 —a condition which could only be brought about when 

 metallic resistance is substituted for the tube, by doubling 

 this resistance. 



This points to the important conclusion that other 

 things being kept constant and the current alone varied, 

 we should find the value of V strictly constant for all 

 values of C j but it may readily be imagined that in 

 experiments with " vacuum tubes " it is not easy to ensure 

 perfect constancy of the accompanying circumstances. 



To test this conclusion we extended the range of our 

 observations by varying the value of C as much as from 

 I to 135. 



In the paper are given the original measurements 

 themselves, not the mean results, in order that the dis- 

 crepancies in the readings obtained for V when C was 

 kept as constant as our powers of control permitted, might 

 be compared with the variations, such as they are, in the 

 values of Fwhen the circuit was purposely varied so as 

 to produce currents of different strengths. Our obser- 

 vations show clearly that discharge through rarefied gases 

 cannot be at all analogous to conduction through metals ; 

 for a wire having a given difference of potential between 

 its ends can permit one — and only one — current to pass ; 

 whereas, from the measurements obtained it became 

 evident that with a given difference of potential between 

 the terminals of a given vacuum tube, currents of strengths 

 varying from i to 135 can flow. We are therefore led to 

 the conclusion that the discharge in a vacuum tube does 

 not differ essentially from that in air and other gases at 

 ordinary atmospheric pressures — that it is, in fact, a dis- 

 ruptive discharge. 



By fixing small rings of tinfoil to the glass near the 

 places where the metal terminals are fused into the tube 

 and connecting these rings to earth, we were able to cut 

 off the leakage over the surface (which, in spite of precau- 

 tions, is considerable), and prevent it from interfering 

 with our measurements of the potential of the gas insiJe 

 the tube. 



{To be continued?) 



NORTHERN BORNEO 



SOME time ago (Nature, vol. xviii. p. 454) we were 

 able to give a few particulars respecting the 

 acquisition, by a British association, of a considerable 

 portion of Northern Borneo, a region which has never 

 yet been thoroughly explored. Under the title of " North 

 Borneo," the promoters of this association have just 

 printed for private circulation a 4to volume, containing 

 a sketch of the territory of Sabah, lately ceded to them, 

 and a report on various portions of the same by a Ceylon 

 planter, which are accompanied by an analysis of soils 

 and three appendices. The volume also contains two 

 maps of Borneo, but the details given therein about the 

 northern part are necessarily meagre. 



The territory of Sabah comprises an area of some 

 18,000 square miles, possessing the great advantage of a 

 coast-line of 500 miles from the Kimanis River on the 

 north-west coast, to the Sibuco River on the east side of 

 the island ; it has the finest and almost only good harbours 

 in Borneo, viz., Gaya Bay, Ambong, and Ousukan Bay 

 on the west, and Sandakan Harbour on the east coast, 

 the first and last named of which will, no doubt, become 

 of great importance, especially if it be true that there is 

 coal close at hand. The whole of Sabah is traversed by 

 a mountain range of 5,000 to 8,000 feet in height, which 

 culminates in the Kini Balu mountain, 13,700 feet high. 

 To the east of this is the supposed position of the Kini 

 Balu Lake, which no European has yet visited. On the 

 shores of the lake, according to native reports, there are 

 many villages of Ida'an, who cultivate cotton, tobacco, 

 &c., and are said to be peaceful and industrious. There 

 are numerous rivers on the north-west coast, but owing 

 to the proximity of the high mountain ranges they are 

 said to be only navigable by light craft ; on the east 

 coast, however, there are several splendid rivers, the 

 Paitan, Sibuco, and Kinabatangan, the latter of which is 

 believed to be navigable by large steamers for several 

 hundred miles. As far as has been at present ascer- ■ 

 tained, the spurs and slopes of the Kini Balu range seem H 

 well fitted for the cultivation of coffee, tea, and cinchona, 

 and the level country on the banks of Kinabatangan for 

 sugar, indigo, tapioca, tobacco, cocoa, cotton, and rice. 

 The Sabah territory is believed to be but sparsely 

 peopled, the total population being estimated at 150,000 

 to 200,000 ; the interior is inhabited by descendants of 

 the aborigines, called variously Muruts, Dusuns, or 

 Ida'an, and corresponding in their external appearance 

 in many respects to the Dyaks of Sarawak and the 

 southern parts of the island, though they are of a lighter 

 hue. The climate of the region is believed to be very 

 favourable ; in the plains and low-lying lands near the 

 sea and rivers an invigorating breeze is generally felt 

 during the day, the thermometer seldom ranging beyond 

 86°, while the nights are cool, with a temperature some- 

 times below 70°. No data are yet available in regard to 

 the rainfall, but it is believed to be very similar to that of 

 Ceylon. The soil is rich and fertile, and in many locali- 



