348 



5. Assuming that the silver nitrate solution is of standard strength and that 5 

 grams of water are taken for analysis, then the number of c.c. of silver nitrate solution 

 required for complete reaction will represent the parts of chlorine per 1000 of water 

 analyzed, without further computation. 



6. By reference to the international hydrogra])hic tables* the parts of chlorine 

 per 1000 (column 1, marked "CI") can be read directh' into total salinity (column 2, 

 marked "S"). This "salinity" represents the oceanic portion of bay waters only and 

 neglects the stream and seepage, or land water, contributions, since the marine borers 

 are only adapted to the normal saline complex of sea water.! All salinit\- results for 

 this survey should lie represented in terms of this calculation of total salinit\-, in parts 

 per 1000, in accordance with these tables. 



Current Record and Disposition. — The results of each weekly or other periodic 

 analyses should be tabulated in triplicate against the data obtained from the tag- 

 label of each water sample. One copy may then be kept by the cooperator, while the 

 remaining two are to be mailed to the U. S. Forest Service, Ferry Building, San 

 Francisco, Calif., attention of C. L. Hill, by whom one set of all analyses will be sent 

 to Professor C. A. Kofoid at the University of California for use in the biological studies. 



II. TEST PIECES 



For the purpose of recording the activity of borers, test pieces of untreated timber 

 will be planted at points to be selected by the Committee or the engineer of the survey. 

 Specifications for making these test pieces are given on the accompanying diagram. 

 The pieces can be put down securely by pushing the end slightly into the mud and 

 tacking the top to a convenient point on the structure by which the test station is 

 located. 



The use of such test pieces, as descril)ed below, is the best means so far devised 

 to make possible continuous information respecting the inception, character, and rate 

 of progress of a marine borer attack at a specified point, and therefore a judgment 

 respecting the probable condition of and the degree of danger to adjacent structures. 

 For this purpose one test piece should be installed each month, beginning preferably, 

 in this climate, with the calendar year or some time during the rainy season, while 

 the salinity is lowest in bay areas affected by land water discharge. Each month 

 there should then be taken oft' from all the test pieces previously installed the bottom 

 saw-cut section (or that one whose position has been next above the mud line), to- 

 gether with the attached redwood block. Except in the case of the first test piece put 

 down, there is no need of keeping a given piece in position more than one >-ear. There 

 will then be obtained each month as many test sections as the number of months 

 during which the test has been in progress, up to one year, and after that a continuing 

 series of 12 sections, of which one was installed during each month of the preceding 

 year. To give continuing inff)rmation on the relative intensity of attack at dift'erent 

 levels, the first piece put down should have the saw-cuts extend not o^'er half through 

 the width of the piece, so as to leave a substantial strip to support all the remaining 



*"Hydrographischf Tabelleii" by Martin l-Ciuulsun; prepared under the authority and direction 

 of the International Council for the Exploration of the Sea. Published by G. E. C. Gad, Copenhagen, 

 1901. The formula on which these tables are based is: S = 1.8050 CI -|- 0.030. 



tTherefore determination of the salinity of brackish waters by the weight of solids left on e\ap- 

 oration is not valid for the purposes of the Marine Borer Survey. 



