78 C. Barns — Coronas with Mercury Light. 



may be derived, for the general reductions in this and other 

 cases where s f is observed. The individual data are omitted. 



With the given value for s the optical data for the diameters 

 of the particles, d'='0Q4:/s and for the nucleation, ?z/ = 120 s% 

 were computed. 



The subsidence constant 



S = s z > (l-s^Jys'J 



was obtained from the observations between 2 = 13 and z = 19, 

 and a mean datum, #=12, accepted as most satisfactory. It is 

 then possible to compute n 09 the original nucleation, as 



n = nj \y* (1-S/O - — (1^-S/*. 1 -,) 5 

 from each of the groups of values specified. The mean results 

 are 



Part V, rt =4 540 000 



Part VI, =3 430 000. 



Knowing n , the series of data for the nucleation n X 10~ 3 

 follow ; from these the diameter 10W=199 ?i-b of fog particles 

 and the apertures s = *004/^ are finally computed. In other 

 words n and d are the data obtained in view of the occurrence 

 of geometric series of nucleations with allowance for subsidence. 



All these results have been constructed graphically in figures 

 2 and 3, for parts V and VI of the above charts respectively. 

 The observed and computed apertures s are first given ; then 

 the observed are optically computed d' and the computed d from 

 sequences appear, and finally the observed or optic n' and the 

 computed nucleation n from sequences. The corresponding 

 data coincide very closely after 9 to 11 exhaustions, i. e. for 

 moderately small coronas : but in the case of large coronas 

 and nucleations, there is marked systematic divergence. A 

 discussion of these results will be given presently. 



Finally, parts VII and VIII of fig. 1 contain measurements 

 of the chord of the angular diameter (radius of goniometer of 

 30 cm ) of the outer edge of the green disc s' and the outer 

 edge of the first ring s' r/ . The minimum may be deduced from 

 s\ since s = -54+1 -06s' has been accepted. From s the optic 

 value of diameter of fog particle d' and the nucleation n' 

 have been computed. The apertures are very fully given in 

 figure 1, in relation to the number z of the exhaustion. The 

 curves are again linear in character, but in case of the outer 

 edge s'" 9 the insufficient size of my fog chambers and the 

 greater vagueness of definition interferes with close measure- 

 ment. The results are 



Part VIIIs' =1-00 4- P07 (I8-2), part VII •*'= -50 + 1-13 (17— 2), 

 s'"=:3-00 + l-93 (I8 — 2), s"'=l-50 + 2-13 (17-2), 



s =1-61 + 1-14(18-2), s .-=1-08 + 1-20 (17 — 2). 



