On the Mensuration of Timber. 217 



a load, but of square or hewn timber fifty feet make a 

 load. 



Notwithstanding the glaring inconsistencies of the two 

 last methods, they are established, and from their facility in 

 practice, especially to those who are expert at operating 

 with duodecimals, and to others when aided by Hoppus' 

 tables and others in use for casting up or performing the 

 numerical operation, or by the still more facile operations 

 of the slide rule, I ha\ r e no hopes of speedily seeing them 

 laid aside and more correct methods introduced ; they will 

 in all probability continue as long as the other heterogeneous, 

 multifarious, and absurd denominations of our measures 

 and weights *. In the mean time it is of importance to the 

 grower, of oak timber in particular, to be able to calculate, 

 in a lot containing a certain number of loads or feet of tim- 

 ber, measured in the round, or as it is generally sold by the 

 grovVer, how many loads or feet the same lot will measure 

 when hewn in any determinate manner {i. e. when the 

 ratio or proportion between A a and £b, fig. 7> is known), 

 and afterwards measured by callipering it, being the mode 

 in which it is measured when purchased in his majesty's 

 dock-yards, and by the private ship and barge builders, &c. 

 in London. As I am not aware that any rules have been 

 laid down, or that any table for this purpose has been pub- 

 lished, I have constructed the following table, consisting of 

 four columns; the first containing the calliper Aa or Aa 

 of hewn timber at the middle or girting place, (see fig. 7,) 

 wherein the diameter Bb or Bb is 1 or 1*00; the numbers 

 herein begin at *70 or 70-100dths of the diameter, (which 

 is something less than a tree can be hewn without absolute 

 waste,) increasing in a regular order by l-100dths to 1*00, of 

 the case in* which the least possible thickness is hewn off the 

 tree : hut it must be remarked in this column, that between 

 this regular series of numbers, *70, *71, *72, &c. other 

 numbers are inserted in their proper places, but carried to a 

 greater number of places of decimals, for showing more ex- 

 actly the proportions in some particular cases mentioned in 



'* The true content of any round tree might be found by the help of 

 tapes and tables constructed for the purpose, in as short a time as it can 

 be measured by the present mode with a string and rule; and simple 

 tables might be made for the allowance for the corners generally wanting 

 in hewn timber, and for showing its true or cubic content. Improved, 

 slide-rules might also he used for the above purposes, instead of tables. 

 A very simple instrument has been made, and used with great success by 

 a friend of mine, Mi. Bevan of Leighton Buzzard, for rinding the true 

 content, or the customary content, allowing for the bark, &c. 



Q^3 the 



