516 Eighth Annual Report of the 



Cooperstown in general show a fairly close agreement; the maxi- 

 mum deviation being 0.9 degrees in May, and that of the annual 

 mean 0.3 degrees. 



It will be seen, finally, that a thoroughly satisfactory )deter- 

 mination of normals for the entire State can not yet be made. 

 Many important localities are represented by but four years of 

 observation, giving an average relative error of from 0.5 degrees 

 to 1 degree for the State at large. The observations novv^ being 

 carried on at numerous stations by members of the State Weather 

 Service may be expected to supply the needed data in the course 

 of a few years. 



Average Rainfall. 



The average vaJues of rainfall given In table 14 were derived 

 from nearly all available records of a leng-'th sufficient tO' subordi- 

 nate accidental to permainent features. The monthly and annual 

 totals for each station were examined, and a few obvionslv in- 

 correct values were omitted from the computations; while re- 

 cords having large systematic differences from thoise of neigh- 

 boring stations were rejected altogether, unless all of the con- 

 ditions attending the observations were known to be satisfac- 

 tory. In most eases however, the records show a general agree- 

 ment as to the characteristic features of rainfall distribution 

 over the State and also conform to definite types of annual 

 fluctuation ; from which it is concluded that accidental errors are 

 not so numerous as to very materially affect the averages. In 

 the majority of cases the observations were made under the 

 direction or general supervision of the Board of Regents or the 

 Smithsonian Institution, and observers were supplied with 

 gauges of a satisfactory pattern. 



An estimate of the reliability of permanence of the averages of 

 table 24 will be of value here. As the result of an extensive 

 investigation of many hundreds of records obtained from all parts 

 Oif the world, Mr. A. Binnie of the Institute of Civil Engineers 

 of Great Britain gives the following probable errors of annual 

 rainfall averages covering various periods: 



