TIMBER CRUISING 



BY P. L. LYFORD 



MOST lumbermen, or persons interested in timber, 

 understand that a "timber cruiser" is one who 

 estimates the quantity and quality of logs or lum- 

 ber contained in standing trees. He is also expected to 

 advise as to topography, logging conditions, and anything 

 else his employer may re- 

 quire to know, which has a 

 bearing on the ability of the 

 tract under consideration to 

 produce logs profitably. 



No doubt the earliest 

 logger was somewhat of a 

 timber cruiser, but he 

 would not have known him- 

 self by that name. It was 

 at a much later day, when 

 the timber "looker" went 

 out on long trips with a 

 map for a chart and a com- 

 pass as the most indis- 

 pensable part of his equip- 

 ment for roaming the track- 

 less forest that someone 

 likened him to a mariner 

 who, similarly, finds his 

 way on the pathless sea, 

 that the term "cruiser" was 

 applied to him. It was an 

 apt comparison, and the 

 term "stuck." 



The quantity of standing 

 timber is usually expressed 

 in board feet, according to 

 the log rule used in the 

 locality concerned. There 

 are some exceptions to this, 

 notably the pulpwood re- 

 gions of the Eastern United 

 States and Canada, where 

 the cord is largely used as 

 a unit of measurement. 

 The cord is also used on the 

 Pacific (oast for measur- 

 ing Cedar Bolts for shin- 

 gles. Theoretically the log 

 rule gives the number of 

 board feet that the logs will 

 produce in the form of 

 sawn lumber. In practice, this is rarely the case, because 

 of imperfections in log rules, errors in allowance for 

 defects, or curved, crooked, or broken logs. However, 

 the cruiser must report in board feet, and it is obvious 

 that his result-, will always be somewhat less than exact. 



in the early days (and even now, to some extent), the 



PACIFIC COAST BALSAM FIR ON THE LEFT AND YELLOW CEDAR 

 OR CYPRESS ON THE RIGHT 



timber cruiser frequently estimated comparatively small 

 areas by eye, simply wandering through the tract more 

 or less systematically, and making up his mind by com- 

 parison with similar tracts with which he was already 

 familiar that this one would run so many thousand feet 



to the acre, and multiply- 

 ing this by the number of 

 acres in the tract to get the 

 total stand of timber. 

 Usually, however, in re- 

 cent years, practically all 

 cruisers make an estimate 

 of the individual trees on a 

 certain proportion of the 

 area, to furnish averages 

 for applying to the whole 

 area. 



The detail of procedure 

 for most cruisers in deter- 

 mining the scale of a tree 

 is somewhat as follows : 

 Estimate the thickness of 

 the bark, and determine the 

 diameter of the butt of the 

 first log inside the bark. 

 (This is not so easy to do 

 on the Pacific Coast where 

 the bark varies from one- 

 half inch on small spruce 

 trees to as much as a foot 

 in some cases on large 

 Douglas fir trees.) Cali- 

 pers or diameter tape may 

 be used to measure diame- 

 ter outside the bark. Next, 

 the taper of the tree is esti- 

 mated so that the diameter 

 inside the bark at the end 

 of the first log may be de- 

 termined. (To get the 

 number of board feet in a 

 log, it is necessary to know 

 the length of the log and 

 the diameter inside the 

 bark at the small end.) 

 This is repeated for each 

 log until the top of the 

 merchantable length is 

 reached. A few inches extra must be allowed for the 

 length of each log in order to provide for full even 

 lengths of lumber when the log is sawed. Now the 

 measurement for each log having been determined, it 

 remains only to read the scale in feet for each log from 

 the log rule table and add the logs together to get the 



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