\\ \ I i.K STAGE REGIST US m 



\\ hen for good reason high priced material* of 

 contftriK -H..II are used, the reduction of tin- dimensions of the 

 cross-set n.. n i.. .; l,y 4 feet may be advantageous, especial 1\ ii 



ii ii p. ihl.- to piovide several .-1111.111. t. th.- s%. II between 



and luw 



The mainiaU ..I construction suitable f.r lining *rll* 

 include (usually treated with a wood preservative), 



-.. Minlini hi,- pipe, concrete plain or reinforced in mass, 

 concrete rings* stone, pipe, riveted sterl J.IJH-. and 



galvanized wrought iron cuU.-rt pipe. 



On the degree of crriamu \%ith \%ln. h the useful life of the 

 -tah.m ma\ IM ,1 will depend die general choice of the 



ni.iiri i.il I- use at any given -iatin, lunger usefulness requiring 

 in- re durable material. The specific choice will depend on 

 the accessibility of the station and on the availability of labor 

 and material. 



In northern latitudes at must be given to the possi* 



li lily of the water in the well freezing, with the consequent 

 interruption of the record, hut in a well properly constructed 

 and placed far enough back from the river there should be no 

 danger from frost, even in temperature as low as 30 degrees 

 below zero. Several methods are available, the choice among 

 them being made on the basis of first cost versus cost of opera- 

 ti* u. Where the first method is used, that of higher first 

 cost, the well i- placed far enough back in the bank to be 

 protected against cold. To obtain this protection the well 

 should be built so that the water surface during the winter 

 season i- .it lea>t two feet below the depth of maximum frost. 

 Guarding against the pos>ihilit\ <>i tr.-ezing allows more 

 freedom in th< , h..iee of observers. 



Where such construction does not seem advisable an oil 

 cover may be applied, using a depth of oil equal to the maxi- 



mum thirkii- -. plu- '2 fe-t. \ |r\ie.- t'.ir mlij, ing the 



quantity of oil required is -h..\\n in r i-. 66. In some cases 

 the device of building a jacket around an exposed well has 

 been resorted to. Between the \%* 11 an. I the jacket a space of 

 t i- l.-tt. \shich i> filled with manure, leaves, or some 

 -imilar material. The jacket is carried up 8 feet above the 

 water surface. 



