A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 147 



weather, shows lowered winter nucleation. The -data are numerous because 

 many subsidiary experiments were made, but little of new import suggested. 



The method of measuring coronas to the outside of the first red ring was 

 adopted on February 16. 



The cold wave beginning on February 18 (chart u) shows moderately 

 high nucleation until it breaks with the thaw on February 21. Thereafter 

 gradual but fluctuating fall of the temperature and nucleation curves appears 

 from February 22 to the intense rain on February 28. During much of the 

 time the ground was covered with snow. Mid-day minima are of common 

 occurrence. 



March 1-15 (chart 12), with its relatively high temperatures, has nearly 

 wiped out the characteristic winter nucleation. The daily nucleation is not 

 very variable and the rain minima are curiously high. The temperature effect 

 is quite vague, there being as much opposition as correspondence. This sudden 

 drop of the winter nucleation in March, ipoj, is particularly noteworthy and it 

 will not be repeated in 1904. The Sunday nucleations in March are not ex- 

 ceptionally low until the 1 5th, when an abnormally small value for a clear day 

 appears. As there is a general cessation of work in factories on this day, the 

 corresponding nucleations are to be carefully scrutinized throughout the period 

 of warm weather following. During cold weather there is no reduced nuclea- 

 tion on Sunday. 



SECOND GROUP OF OBSERVATIONS. 



6. Arrangement of tables and graphs. On the i2th of March the same 

 apparatus was installed in a new position, and on March 1 5 the results referred 

 to above, 3, as the "second gruop," begin. The scale is uniform throughout, 

 though somewhat enlarged, and the plan is the same as above. Local winds and 

 temperatures only are entered. 



The data are also given in tables, as it is believed that the method is now 

 sufficiently definite to make these available for other purposes than the im- 

 mediate ones of the present chapter. The tables contain the date and hour, 

 the state of the weather, the temperature of the atmosphere where the nuclea- 

 tion is observed in degrees Fahrenheit, and of the air within the apparatus in 

 degrees centigrade; furthermore, the aperture, s, of the coronas when the 

 goniometer radius is 19.5 cm. and the distance of the goniometer and source of 

 light 85 cm. and 250 cm., respectively, from the condensation chamber. Thus 

 the angular diameter is <p = z sin" 1 (5/39). The remaining columns contain the 

 coronas with the colors recorded from within outward, abbreviated as stated, 

 and the absolute nucleation, n, or number of nuclei per cubic centimeter of air. 

 Certain obvious remarks will be added. 



The correction for the temperature of the condensation chamber (pur- 

 posely kept as nearly constant as possible) was not applied. This would have 

 enormously increased the labor of reduction, without materially changing the 



