Experiments on the Strength of Woods, by Mr. Barlow, Jun. 1 8 1 



timber, and it is the opinion of persons on the spot that they 

 were both planted together. 



Thus far the experiments were made with a particular ob- 

 ject; but as there were in store, in the Royal Arsenal, many 

 woods, not in very common use, but which are grown abun- 

 dantly in some countries, and from the appearance of which 

 great strength was anticipated, Mr. Bossey, foreman in the 

 carriage department, was requested to prepare specimens, 

 which were submitted to the same test as the former ones. 



These results are interesting, some of the woods being more 

 than double the average strength of oak : several of these spe- 

 cimens were sent from Berbice by Capt. Gipps of the Royal 

 Engineers, who speaks very highly of their durability. 



The apparatus made use of in the experiments consisted 

 simply of two upright posts, fixed securely at one end in the 

 ground, and at the other to the tie beam of the roof of ashed; 

 on each of these were firmly attached two pieces of hard wood 

 formed to an edge, on which the specimens to be experim.ented 

 upon were placed, and a scale suspended from the centre to 

 receive weio-hts. To ascertain the relative stiffness or elasti- 

 city, the weight which caused a deflection of one inch, was 

 registered, which was denoted by a rod attached to the tie 

 beam so as to point downwards in front of the middle of the 

 specimen, and one inch below the upper surface; so that when 

 one inch of deflection had taken place, it was shown by the 

 rod just passing clear of the piece under experiment. 



In the Table, the 1st column contains the names of the 

 woods; the 2nd the specific gravity; the .3rd the weight which 

 caused 1 inch deflection, or j^j^ih part of the length ; the 4<th, 

 the breaking weight; the 5th, the relative elasticity from the 



formula E = — ,^- ; the 6th, the strength from the formula 



add 



S = — ^ ; where I is the length, a the breadth, d the depth, 



l the deflection in inches, and tc the weight in pounds; by 

 which they become comparative with the various experiments 

 in Barlow's Essay on the Strength of Timber ; and the last co- 

 lumn contains any requisite description or remarks. 



The pieces were each accurately cut and planed 2 inches 

 square, and 5 feet in lengUi ; and the distance of the props on 

 which they were broken was exactly 50 inches: they were 

 selected with great care by Mr. Bossey, who assisted at the 

 experiments, and registered and delivered the following re- 

 sults. 



Table 



