10 



Atmoraetry and the oorous cup atmonieter . I b j d . 18:21-30, 

 51-74, 9.5--111, 1^..3-149.lyl.) 



■-"h'^cr''' -ti ons nentionefl aToove, only t'lree rfi 11 "be conslfiered 

 here, narael:^ those of temperature, light, and evaporation. 

 As was pointed out by Mclean, rainfall f^howed little or no 

 relation to the growth of these -slants, since the soil mois- 

 ture of the cultures was always kept sufficiently high' ("by 

 the auto-irrigators) for the needs of the plants. The main 

 influence usually thought of as exerted by rain uoon slants 

 is of course an indirect one; the rain does not affect the 



plants but it alters the soil moisture condition and *-he al- 

 teration thus brought about influences the vSn.pply of v;ater avail- 

 able to thfe plant roots. :ainfall data will therefore not 

 be dealt with in thife paper. Also, the miscellaneous cliraatol- 

 ogical observations reported bv -^he weather observers "'ill 

 not be considered since none of tiiem have been found to bear 

 any relation to the growth of these plants. 



The mass of climatic data, instruinantal In the case of 

 evaporation and temperature, and observational in the case of 

 light, can obviously not be compared with plant growth until 

 it is simplified in -"ome way. '"he process of p i-riol i ''in^ition 

 here adapted involves two main steps. The first of these con- 

 sists in bringing together the daily observations into t^-o- 

 week and four-we'-^k -roups corresoonding to the two anfi fox<r- 

 Yieek growing periods, i :' way in which to do this, -'^i' instance, 

 is to average the daily readings over the two-week or the four- 

 v/eek period, ■^hus securing an avera^^'e ."iaily value for the 



