180 



SCIENCE. 



[N. S. Vol. XXIV. No. 606. 



ance of blue lights," says Professor Larkin, 

 "was over a wider area than at first thought. 

 At Petaluma * * * blue flames eighteen inches 

 in height played over a wide expanse of marsh 

 land." Before the earthquake only " a flick- 

 ering ominous haze was seen playing above 

 the ground." "A dark funnel-shaped mass 

 was seen in Fourth Street, San Francisco, 

 suspended in the air, and it was illuminated 

 by scintillating lights, like fire-flies." " Blue 

 flames were seen hovering over the bases of 

 foothills in western San Francisco." In San 

 Jose, on the street called the Alameda, look- 

 ing eastward, at the time of the shock the 

 whole street was seen " ablaze with fire, it 

 being of a beautiful rainbow color but faint. 

 This, no doubt," observes Professor Larkin, 

 " was an electrical display, for had gas been 

 on fire all along the street the houses would 

 have been ignited. And letters from a point 

 north of San Francisco describe blue lights as 

 flickering like an aurora over a wide area of 

 marsh land with a troubled surface of adjoin- 

 ing water. And can it be that the giant 

 Electricity took part in the vast seismic tur- 

 bulence? * * * The writer scarcely knows 

 which one of the multitude of theories regard- 

 ing the cause of earthquakes to adopt." 



Later Professor Larkin grows more confi- 

 dent and asserts that " the San Francisco 

 earthquake was due to a readjustment of the 

 edge of the layers once torn apart when the 

 earth was young. * * * It appears that two 

 faults were involved. * * * I do not wish to 

 assert that the earth's charge of electricity 

 helped in the havoc, but believe that it did. 

 That giant is able to do any vast work." 



No wonder that in Professor Larkin's mind 

 ' great questions arise.' " Did man appear 

 on earth before his dwelling was ready ? Does 

 nature care whether man exists? It is as- 

 serted that she has slain thirteen million hu- 

 man beings by convulsive force alone within 

 the historic period." 



' Swing low. Sweet Chariot,' sings Professor 

 Larkin, with cheerful relevance. And, indeed, 

 when we stop to think of it, why not? 



D. S. J. 



SPECIAL ARTICLES. 



TIME VARIATION OF THE INITIAL NUCLEATION OF 



WET DUST-FREE AIR. 



In the further development of the investi- 

 gation ^ on the time variations of the efficient 

 colloidal nucleation in filtered air, I find re- 

 sults of the same character as those already 

 discussed ; but the dependence of the nucleation 

 on the fluctuations of the barometer shows 

 itself even more obstrusively than before. 

 The minima of atmospheric pressure coincide 

 with maxima of the larger colloidal nuclea- 

 tion and therefore (by inference but not neces- 

 sarily) with minima of ionization of the dust- 

 free air, both in the daily and in the weekly 

 periods of observations. Maximum pressure 

 would correspond to maximum ionization as 

 if the radiant energy originated in the com- 

 pression of the atmosphere, or were dependent 

 on the mass of the atmosphere bearing on a 

 given place. This would, if finally sub- 

 stantiated, be an important result, but no laore 

 so than the correlative result that minimum 

 pressure and maximum of the initial colloidal 

 nucleation of dust-free air go together. The 

 bearing of this on ' adsorption ' of atmospheric 

 ionization will be stated presently. 



At the same time since the change of ab- 

 solute temperature, t, due to sudden expansion 

 equivalent to a drop 8p at a barometric pres- 

 sure p and vapor pressure tt may be vsrritten 



tji^ = (1 — 6pl{p — n))(k-e)ic 



the correction for the changes of the barom- 

 eter are in the same sense as the observed 

 changes in nucleation. These corrections are 

 found by varying the numerator of Sp/(p — tt) 

 and observing the effect on the angular diam- 

 eter of the corona. While I see no room for 

 error, it must nevertheless be acknowledged 

 that the present method of small exhaustion 

 (though possibly more sensitive) is not as 

 straightforward as the method mentioned in 

 my address where no variation could be de- 

 tected, the terminal corona remaining un- 

 changed. 



At the present stage of investigation, there- 

 fore, the need of any cosmical radiation has 

 ceased to be obvious and should be abandoned, 



^Science, XXIII., p. 952, 1906. 



