NO. 9 



BRIGHTNESS OF LUNAR ECLIPSES — FISHER 



43 



and the western, or sunset side. In the scanty allusions to this point, 

 observers frequently disagree about identical eclipses, or record the 

 phenomena in some cases one way, sometimes the other ; and some 

 definitely state that no difference was observed. 



Figure i is an attempt to show some of the preceding relations 

 graphically. The abscissas are time, in years ; the date number stands 

 for Jan. i in each year, so that the year interval extends to the right 

 of each number. The upper curve is Kimball's radiation curve, with 

 per cents as ordinates. The next (broken) line connects points 



Fig. I. 



representing solar maxima and minima, from Wolf -Wolf ers and See ; 

 there is no attempt to represent amplitudes of the true sunspot curve. 

 Three lines marked N, C, S, carry circles representing lunar eclipses, 

 north, central and south ; a black circle represents grade o, a half-black, 

 grade i, a white circle, grade 2. Volcanic eruptions are marked with 

 dots on a horizontal base line; where data could be found, the height 

 of the eruption cloud in kilometers is represented by a line drawn 

 upward from the base, the maximum spread of the ash-fall in statute 

 miles by a line drawn downward ; arrowheads on either of these 

 upward or downward lines indicate that the amount represented is 

 doubtless too small. Thus, the Katmai cloud was seen at Cook Inlet, 



