Mar. 1 6, iSSS,] 



SCIENTIFIC NE^A^S. 



257 



on the coast-line ; and, finally, an exhaustive list of the 

 flora of the Laramie Group, by Lester F. Ward, illus- 

 trated by some sixty large plates representing fossil leaves, 

 mostly of dicotyledons, obtained from this formation. 



Transactions of the Mancliester Geological Society. Vol. 

 xix. Parts xii. and xiii. 



The former of these parts is taken up with the inau- 

 gural address of the President, Mr. Joseph Dickinson. 

 The first part of this address treats rather briefly of the 

 general progress of geology. He raises, however, some 

 interesting questions. He asks if there is any instance 

 that rock salt has been actually penetrated underneath 

 the lias ? He asks, why do the lowest geological forma- 

 tions ordinarily occupy the highest elevations above sea 

 level ? Why should rivers commonly flow from the 

 lowest to newer formations ? 



On mining, that is, from a South Lancashire point of 

 view, coal-mining, he expatiates at very considerable 

 length. He mentions the very curious fact that at 

 shallow depths, in very ancient workings, in the iron-ore 

 of the Forest of Dean, spades cut out of solid wood have 

 been found without any appearance of having ever been 

 tipped with iron. After a reference to the work of 

 Agricola on mining, written more than three centuries 

 ago, he passes to his main subject, " Mine explosions and 

 their prevention." A curious fact brought out is, that 

 the mortality among copper, tin, and lead miners, who 

 are in no danger from explosions, is greater than that 

 among coal-miners at all ages. Between the ages of 

 forty-five and fifty-five, for instance, it is almost exactly 

 double. And yet the metal miners, unless we are very 

 much misinformed, are intellectually and morally a class 

 very much superior to the colliers. 



The underground temperature at the depth of 50 feet 

 is given as 50° Fahr., which is about the yearly average 

 temperature of the air in the shade, at least in the South 

 cf England. In the coal districts, the mean rise of tem- 

 perature on descending is 1° Fahr. for every 60 feet of 

 depth. Consequently at the depth of 4,000 feet, which is 

 taken as the maximum depth at which coal-mining is 

 practicable, the temperature would be no'' Fahr. 



The older safety lamps, the Davy, the Stephenson, and 

 the Olanny, are now being rapidly superseded by the 

 Mueseler, the " Protector," and the Marsent. 



In Part xiii. the question is raised in how far the earth 

 tremors observed in the neighbourhood of Sunderland 

 are connected with the pumping of water from the mag- 

 nesian limestone, and again whether the earthquakes 

 which are said to have lately occurred in Lancashire are 

 due to old coal-workings. A further question for examina- 

 tion is how far beneath the surface these tremors extend. 



The bulk of this Part is, however, devoted to a paper 

 by Mr. W. Cliftbrd, on the Richmond Coal-fields, Virginia. 



Worthy of Imitation.— The Russian Minister of Ways 

 of Communication has appointed a special commission to 

 select the best system of electric lighting for railway car- 

 riages. This is the result of a decision recently arrived at 

 to render the adoption of the electric light compulsory upon 

 the principal railway companies for all passenger trains. 

 The experiments will be conducted on the Nicolaieff Railway, 

 and are not expected to last more than a month. The South 

 Russian Railway Company, it should be noted, has already 

 adopted the electric light for all fast trains running between 

 Odessa and Kieff, while it has been used in the special 

 Imperial trains for some time past. — Electrical Review. 



THE TIME IN WHICH WE THINK. 



ONE of the most beautiful applications ol electricity 

 which has of late been made is its use in the study 

 of psychological phenomena. And why, indeed, is not 

 the subtile power by which time and space are being 

 annihilated, and human labour rendered less irksome, 

 the most proper agent to assist man in the study of facts 

 of his own consciousness ? In an elaborate article in the 

 Nineteenth Century, Dr. J. McK. Cattell gives an account 

 of the time-measurements of thought, made by means of 

 a line drawn on a rapidly moving surface by a pen attached 

 to the prong of a tuning-fork, vibrating at a constant rate, 

 by means of electricity. By a delicate apparatus con- 

 structed on this principle, duration of time may be 

 measured to the one ten-thousandth of a second. The 

 writer above-named has found that the process of 

 thought varies in its degree of rapidity in different indi- 

 viduals, children and old persons thinking slower than 

 people of middle age, ignorant persons thinking more 

 slowly than educated persons. In this way he also 

 found he could measure the time it takes to perceive ; 

 that is, the time which passes from the moment when the im- 

 pression reaches consciousness until the moment at which 

 we know what it is. In his own case he found that it took 

 1-20 second to see white light, i-io second to see a picture, 

 1-8 to see a letter, and 1-7 to see a word. It takes 

 longer to see a rare word than a common word, or a word 

 foreign language than in our native tongue. It even 

 takes longer to see some letters than others. " Will 

 time," or time taken up in choosing, can be measured. It 

 takes i-i 3 second to judge between blue and red. To recall 

 the name of a printed word takes 1-9 second, of a letter 1-6 

 second, of a picture 1-4 second. It takes less time to re- 

 member the name of a familiar word than a letter, though 

 it takes less time to see the letter. The time of remem- 

 bering can be measured. It takes 1-4 second to translate a 

 word from one language to another when you are 

 familiar with both. It takes 1-20 second longer to 

 translate a word from a foreign language to your native 

 tongue than it does in the other direction. We can think 

 of the name of the next month in half the time we can 

 think of the last month. It has been demonstrated that 

 sensation does not travel through the nerves to the brain 

 so fast as has been supposed. Its speed is not much 

 greater than sixty miles an hour. — Light and Heat. 



Decay Proof Fabrics. — A Belgian, residing in 

 America, proposes to make fabrics almost proof against 

 decay, no matter what their colour or texture may be. 

 He has been studying the headbands of Egyptian mum- 

 mies, which are invariably found in a v/onderful state of 

 preservation, and he discovered that the substance with 

 which they are impregnated is a kind of resin. He then 

 made a series of experiments with the substance extracted 

 from birch bark, to which the peculiar aroma of Russian 

 leather is attributable. In the end it was discovered — 

 so the story goes — that the green tar which was left over 

 after the oil used in tanning had been extracted trom the 

 white bark of the birch tree would yield neither acid nor 

 alkaloid, and that it would, in solution with alcohol, form 

 a liquid of remarkable fluidity, but with the power of 

 resisting, after once drying, even the action of alcohol 

 itself. This is the substance which is to unite with the 

 most delicate or brilliant colours, which wifl not impair 

 the softness of the finest fabrics, and yet will make them 

 nearly indestructible. 



