CYCLOGRAM ANALYSIS 



45 



through coordinate paper whose back was painted with opaque material. 

 This was used in front of a long ground-glass behind which lights were placed. 

 The present process of making a cycleplot ready for analysis has the origi- 

 nal data plotted on a standard scale coordinate paper whose smaller division, 

 2 mm., commonly represents one year. This plot is Hanned graphically and 

 then the Hanned line is traced over carbon paper upon a strip of heavy brown 

 paper 4 inches wide and some 48 inches long. A "cutting" line is marked in 



mm. 



2.0 



i.o 



1820 



30 



4-0 



1850 



60 



70 



80 



90 



1900 



10 



Fig. 23— Cycleplot, to show cutting line. Standardized tree growth, 

 G 5, Eberswalde, Germany. 



' Images of 



** original 



maxima 



— lOyear cycle 



2 Wj /* 



I2year cycle 



Fig. 24 — The analyzing plate changes longitudinal displacement 

 in position of maxima, to transverse. 



a nearly straight line along the minima and the maxima cut out above this 

 line with a razor blade. In this way the maxima are sufficiently isolated so 

 that they can easily be distinguished. If the original base at zero is used, 

 too much light floods the pattern and the maxima are not distinguishable by 

 the eye, as was the trouble with the patterns shown in Volume I (Climatic 

 Cycles and Tree Growth), Plate 12. 



