yune 14, 1883] 



NA TURE 



165 



when required. Also, just as the vibrating sticks can 1 e limed 

 to one another by sliding weights along them, so the vibrating 

 electric meters can be regulated to one another, so that all shall 

 indicate the same value for the same currenr, by changing the 

 I o ition or weight of the bobs attached to the vibrating arm. 



The other meter of this class, Dr. Hopkinson's, depends on 

 the fact that centrifugal force is proportional to the square of 

 the angular velocity. He therefore allows a little motor to 

 drive a shaft faster and faster, until centrifugal force overcomes 

 electromagnetic attraction, when the action of the motor ceases. 

 The number of turns of the motor is a mea-ure of the quantity 

 of electricity that has passed. 



1 will qow pass on to the measurement of power transmitted 

 by belling. The transmission of power by a strap is familiar lo 

 every one in a treadle sewing-machine or an ordinary lathe. 

 The driving force depends on the difference in the tightness of 

 the two sides of the belt, and the power transmitted is equal to 

 this difference multiplied by the speed ; a power-meter must, 

 therefore, solve this problem — it must subtract the tightne-s of 

 one side from the lightness of the other side, multiply the differ- 

 ence by the speed at every instant, and add all the products 

 together, continuously representing the growing amount on a 

 dial. I shall now show for the first time an instrument that I 

 have devised, that will do all this in the simplest possible 

 manner. I have here two wheels connected by a driving 

 band of indiarubber, round which I have tied every few 

 inches a piece of white silk ribbon. I shall turn one a little 

 way, and hold the other. The driving force is indicated by a 

 difference of stretching, the pieces of silk are much further apart 

 on the tight side than they are on the loose. 1 shall now turn 

 the handle and cause the wheels to revolve ; the motion of the 

 band is visible to all. The indiarubber is travelling faster on 

 the tight side than on the loose side, nearly twice as fast ; this 

 must be so, for as there i> le s material on the tight side than on 

 the loose, there would be a gradual accumulation of the india- 

 rubber round the driven pulley, if they travelled at the same 

 speed ; since there is no accumulation, the tight side must ti avel 

 the faste-t. Now it may be shown mathematically that the 

 difference in the speeds is proportional b4h to the actual speed 

 and to the driving strain ; it is therefore a measure of the power 

 or work being transmitted, and the difference in the distance 

 travelled is a measure of the work done. I have here a work- 

 ing machine which shows directly on a dial the amount of 

 work done ; this I will show in action directly. Instead of 

 indiarubber, elastic steel is used. Since the driving-pudey has 

 the velocity of the tight side, and the driven of the loose side of 

 the belt, the difference in the number of their turns, if ihey are 

 of equal size, will measure the work. This difference I measure 

 by differential gearing which actuates a hand on a dial. I may 

 turn the handle as fast as I please ; the index does not m \ e, 

 for no work is being done. I may hold the wheel and pro- 

 duce a great driving strain ; again the index remains at rest, 

 for no work is being done. I now turn the handle quickly, and 

 lightly touch the driven wheel with my finger. The resistance, 

 small though it is, has to be overcome ; a minute amount of 

 work is being done, the index creeps round gently. I will now 

 put more pressure on my finger, more work is being done, the 

 index is moving faster; whether I increase the speed or the 

 resi tance the index turns faster; its rate of motion measures 

 the power, and the distance it has moved, or the number of 

 turns, measures the work done. That this is so I will shi 

 an experiment. I v. ill wind up in front of a scale a 7 lb. weight ; 

 the hand has turned one-third round. I will now wind a 28 lb. 

 weight up the same height ; the hand has turned four-thirds of 

 a turn. There are other points of a practical nature with regard 

 to this invention which I cannot now describe. 



There is one other class of instruments which I have developed 

 of which time will let me say very little. The object of this 

 class of instruments is to divide the speed with which two regis- 

 trations are being effected, and continuously record the quotient. 

 In the instrument on the table two iron cones are caused to 

 rotate in time with the registration ; a magnetised steel reel 

 hangs on below. This reel turns about, and runs up or down 

 the cones until it finds a place at which it can roll at case. Its 

 position at once indicates the ratio of the speeds which w ill be 

 efficiency, horse-power per hour, or one thing in terms of 

 another. Just as the integrators are derived from the steering 

 of an ordinary bicycle, so this instrument is derived from the 

 double steering of the ' ' Otto " bicycle. 



Though I am afraid that I have not succeeded in the short 



time at my disposal in making clear all the points on which I 

 have touched, yet I hope that I have done something lo remove 

 the very prevalent opinion that meters for power and electricity 

 do not exist. 



THE PERMIAN SYSTEM IN RUSSIA > 



A QUESTION which has during the last few years occupied 

 •^ Russian geologists is whether the upper horizon of the 

 " motlled marls," which were considered by Murchison as Per- 

 mian, must be still regarded as such, or rather as a member 

 of the Tnas — an opinion strongly advocated by several eminei t 

 geologists in Russia. The question is a lar^e 1 lie, the mottled 

 marls being the most widely-spread member of Murchison's 

 Permian formation in Russia, and covering it almost on the 

 whole of the surface it occupies in Russia in Europe. Were the 

 Triassic origin of the mottled marls an established fact, the 

 whule aspect of a geological map of Russia would be changed, 

 and so it was on the map published in iS7oby a late member of ihe 

 Acadeuiy, M. Helmersen, and on the map of the western slope 

 of the Ural Mountains by Prof. Meller. The question is thus 

 the subject of much controversy, and a whole series of papers 

 is devoted to it in the Memoirs of the Kazan Society oj Naturalists 

 and elsewhere. The last of this series is a paper by Frof. 

 Stuckenberg, which slates the present aspect ef the question 

 and enables us to summari-e the controversy in its broad 

 features. 



Murchison's Permian system covers, as is known, no less than 

 6600 square miles in eastern Russia, from the province of Arch- 

 angel in the north to that of Ufa in the -outh, and from 

 Nijni-Novgorod in the west to Perm and Orenburg in the east ; 

 isolated islands of it appear on the surface in the provinces of 

 Asliakhan, Kharkov, and Ekaterinoslav. The evidence it- elf 

 of the basin where the Permian formation was deposited neces- 

 sarily implies a great variety of lithological characters, and in 

 fact it includes, besides the dolomitic limestones, a very great 

 variety of marls, clays, sandstones, and conglomerates, the lime- 

 stones occupying separate basins in the middle parts, whilst the 

 marls, clays, sandstones, and conglomerates have the appearance 

 of coast deposits of the Permian Sea. 



In the central parts of the ba-in (Kazan, Samara), the dolo- 

 mitic limestones are covered with a thick sheet of mottled marls, 

 w ith sandstones, conglomerates, clays, and i-olated thinner sheets 

 of a tuff-like limestone. This series covers, however, not only 

 the dolomitic limestone but also, as has been said, nearly the 

 whole of the Permian deposits of Euro[ ean Russia, confounding 

 itself with the Permian marls and sandstones, as is, for instance, 

 the case — M. Stuckenberg say. — in the provinces of Vyatka, 

 Nijni-Novgorod, Kazan, and Samara. Palaeontological evidence, 

 however, is scarce as to the upper mottled marls, so that Murchi- 

 son himself made the suggestion that they may belong perhaps 

 to a more recent formation ; he even proposed to give them on 

 his map a lighter colour than the remainder of the Permian 

 formation. 



The mottled marls were considered as Permian until 1855, 

 when Prof. Wagner published a geological map in which he 

 classified them as Triassic. Later on, Marcou, in 1S5S, and 

 Lndwig, in his " Dias and Trias," in 1S59, arrived, independ- 

 ently of Prof. Wagner, at the same conclusion. In 1864 Prof. 

 Barbot de Marny discovered in a sandstone belonging to this 

 group a fragment of an Equisetites columnaris, Sternb. (Cata- 

 mites arenaceus, Brongn.), and this discovery, confirming former 

 stratigraphical and lithological con-ideration-, induced the 

 majority of Russian ge logists to consider since the mottled 

 mails as a part of the Trias. This view was adopted, as said, 

 by Helmersen and by Prof. Meller. But still, as the mottled 

 marls are very poor in organic remains, and the whole question 

 beset with difficulties, the controversy continued. Murchison 

 found in these marls small Cytherina and shells like Cyclas, 

 together with some remains of fishes and casts of Mytilus. Prof. 

 Golovkinsky discovered microscopic remains of crustaceans and 

 some fragments of shells, whilst the late M. Eichwald found 

 remains ai^Estheria txigua and Beyrichia Pyrrhae, in a deposit 

 which M. Stuckenberg considers as belonging to the same group. 

 As to the find by Prof. Wagner of the Voltzia heterophylla at 

 Abdi, close by Mamadysh, together with remains of the fishes 

 Amblypterus Alberti and Saarichthys Mougeoti, M. Stuckenberg 



1 " The Upper Mottled Marls and their Relations to other Members of 

 the Permian System," by A. irtuckenoerg. (Memoirso/ the Kazan Sociei 

 of Naturalists, vol. xi. fasc. 2 ; Kazan, 1882. 



