x568 



NATURE 



\OcL 24, 1878 



annual appropriations of about $75,000. I know him to be 

 an indomitable worker in the field, and well remember the day 

 when his annual arrival in our department rwas hailed with the 

 greatest interest, and was the signal for every possible act of 

 kindness and assistance from one end of the command to the 

 other. 



Prof. Geikie's quotation, that the presence of an armed escort 

 needlessly irritated the hostile Indians, is out of the pale of 

 decent characterisation. In those days army men were of the 

 opinion that no party having less than 100 long-range breech- 

 loading rifles could safely pass into certain portions of the Sioux 

 country, and that minimum-sized parties could just about take 

 care of themselves on the defensive. That was the basis upon 

 which my party was organised. That there was some error 

 in this judgment was shown by the Custer massacre not long 

 after. To the other portion of the quotation, that the geologists 

 of the Interior Department were never molested by Indians, I 

 will state, from personal knowledge, that they have always taken 

 the most precious care not to operate in the neighbourhood of 

 dangerous Indians, a very sensible proceeding for parties without 

 armed escort. Through carelessness and lack of knowledge of the 

 syste n of guarding camps, they have been stampeded once or 

 twice by thieving Indians who were after plunder, but did not 

 dare to kill anybody. This misfortune has recently befallen 

 them in Yellowstone Park, where the commonest precautions 

 would have made it impossible. Their presence alone, without 

 armed escort, seems to have been " irritating to the Indians." 



W. A. Jones 



Geological Climate and Geological Time 



I HAVE been much interested in Prof. Ilaughton's com- 

 munication to Nature, vol. xviii. p. 266, on the subject of 

 geological climate and geological time. I fully agree with him 

 that geological climates cannot be explained by any change in 

 the position of the poles, even supposing such change possible, 

 and for the reason assigned by him, viz., that we have no palse- 

 ontological evidence of an arctic climate in any portion of the 

 earth in any geological period previous to the glacial. But I 

 have some objections to make to the data on which he bases his 

 estimates of time, and therefore to his views as to the cause of 

 geological climates. 



I. He supposes aqueous agencies to commence operation, and 

 therefore the archoean (azoic) era to commence when the earth 

 surface had cooled to 212° F., evidently because, as he thinks, 

 water could not exist as a liquid on the earth's surface at a 

 higher temperature. But the writer forgets that with all the 

 water of the ocean in the air as vapour, and the large quantity 

 of carbonic acid now existing in the form of carbon and the 

 carbonates also in the air, the pressure of the primeval atmo- 

 sphere must have been many times — perhaps several hundred 

 times — greater than now, and the boiling, or rather precipi- 

 tating, point of water very much higher than 212°. 



II. A^rain : Even with a surface temperature from internal 

 causes of 212°, the crust of the earth must have been very ihin, 

 not more than 40-50 ft. (for increased atmospheric pressure, 

 thou^jh greatly affecting the boiling-point of water, would not 

 sensibly affect the fusing-point of rocks). Under these con- 

 ditions — by the law of equilibrium— the inequalities consti- 

 tuting land-surfaces and ocean-bottoms could not possibly exist ; 

 the ocean would be universal, and therefore there would be no 

 erosion and sedimentation. Therefore when dry land first 

 appeared and erosive agencies commenced to act at the begin- 

 ning of the azoic era, the surface temperature from internal 

 causes must have been much less than 212°. For my part I 

 believe that this temperature had already become very small, the 

 surface had become substantially cool, and the crust very thick 

 before land could exist, and ^the history recorded in stratified 

 rocks could commence. 



III. Therefore, though I agree with Prof. Haughton that all 

 the evidence we have indicates uniform climates in early geo- 

 logical times, I would not, like him, attribute this to warm 

 decrease of surface temperature from internal causes alone. I 

 would attribute it almost wholly to external causes. Among 

 these are: — i. 'Y\:l'S. constitution of the atmosphere. The greater 

 amount of carbonic acid and water in the atmosphere would 

 shut in and accumulate the sun's heat on the earth surface accord- 

 ing to the principle discovered by Tyndall, and applied to the 

 explanation of geological climates by Sterry Hunt. 2. It is 

 probable that the heat received from the sun was much greater 



then than now ; for the sun is now cooling, and has been cooling 

 throughout all geological times much faster than the earth. 3. 

 The idea of Poisson, that in the journey of our system through 

 the stellar universe it may be noiv in a region in which the heat 

 received from sface is exceptionally small, has been, perhaps, too 

 much neglected in these speculations concerning geological 

 climates. 4. The more uniform distribution of this greater 

 surface -temperature from any or .all these causes, would of 

 course still farther increase the temperature of high latitudes. 

 This more uniform distribution might be due to the position 

 and shape of land masses, or to the less area and the less height 

 of the then lands. 



IV. Lastly : I think that a little reflection will show that while 

 it may be allowable to roughly estimate the relative lengths of 

 different eras by the relative extreme thickness of their strata ; it 

 will not at all do to estimate the absolute length of geological 

 times by the extreme thickness of all the strata. For as the mea- 

 suring rod is not the rate at which sediments are now accumu- 

 lating at any one place, but the average rate over the whole 

 bottom of the sea, so the thing to be measured is not the extreme 

 thdckaess of the strata at any one place, much less the extreme 

 thicknesses of different formations in different places piled one 

 atop the other, but the average thickness of the strata over the 

 whole earth surface. 



Most of the points brought out here have already been dis 

 cussed by me in my recently published " Elements of Geology." 



Joseph Le Conte 



University of California, October 2 



The Magnetic Storm of May 14, 1878 



I WAS much interested in Mr. Perry's note inserted in 

 Nature, vol. xviii. p. 617, showing the simultaneity of the 

 magnetic storm of May 14, 1878, in different parts of the 

 earth's surface. As these magnetic disturbances are always 

 accompanied by electric disturbances (earth currents) in tele- 

 graph wires, I was anxious to find out what effects were observed 

 upon our wires in England on the same day, viz., May 14. I 

 append an extract from the diary of the Relay Station at Haver- 

 fordwest, a very important station on the wires running from 

 London to Valentia, and where very careful observations are 

 made of all interferences with the regularity of the working of 

 the wires : — 



May 14. 

 P.M. 

 6.40. — First appearance of relays not closing automatic switch 



well on down side of 202. 

 7.10. — London finds some difficulty in reading on 199; no 



cause visible here. 

 7,40. — Up side of automatic switch on 202 rather unsteady. 

 9.0. — Variations in London's current on 200. 

 9.10. — Strong positive deflections (earth currents) on Cork 



wires. 

 9.15. — Cork complains of marks missing and running; no 



doubt the result of deflections. 

 9,30. — Great difficulty with automatic switches on Cork wires 

 owing to continuous strong positive deflections which 

 ^ ^ tend to opening of switches when battery currents 



are in opposite directions, and to close them when 

 in same direction. Probably earth-currents influ- 

 enced them earlier in evening. , 

 9.40. — Deflections diminishing ; wires going better. 

 9.45. — Deflections ceased. ^>.i s 1 

 1 0.0. — All wires going well ; weather wet. 5 

 10. 10. — Aurora Borealis visible about this time. 

 11.25. — Earth currents very strong again on all wires, causing 

 much trouble with automatic switches. Almost full 

 deflection on up side of 201 and 202. 

 10.40.— Deflection on 202 reversed, and not so strong as 



before. 

 10.45. — Full deflection on up side of 202. 

 10.48. — Deflection on 199 causes up automatic switch to remain 



depressed. 

 M I D N . —Earth currentsdisappear ing. 



May 15. 

 A.M. 



12.40. — Electric storm seems to have spent_itself. 

 fine ; clear moonlit sky. 



Weather 



