38 



CLIMATIC CYCLES AND TREE GROWTH 



such as 1845 and in its proper place on the horizontal axis give it an ordinate 

 of 5 years from 1840, we also plot it at 15 years as a residual from 1830 and 



30 



20 



10 



•b 10 



2 



20 



i 1 1 1 1 1 1 1 1 1 



W///// 



I I I L 



X_J I L 



1850 



1900 



Fig. 19 — a, b. Cyclogram demonstration, second part. 



at — 5 years as a residual from 1850, and so on for a number of repetitions in 

 a vertical line. Thus we build a pattern that repeats itself. This gives a 

 chance to see other cycles beside the one being plotted. 



