1817.) Experiments on the Strength of Wood. 305 
Weigbt. |Curvature. | Difference. |No. 25. 
——. 
ul i 
ae ay OF hs See Section of the piece of pitch pine out of 
42 0 92 0 08 which the 25 pieces were cut, and the mean 
56 0 30! 0 os weight each piece bore. 
10 0 38 0 08 OE ae TY CIES 7 
84 0 46 0 08 1 2 3 4 5 is 
98 | 0 54/ 0 08 153-7 | 145°8| 147 | 139-5 | 151-9} 159-6 
112 1 02 0 08 
196 In le 0 10 A 12 ll 10 9 8 a 
140 1 22] 0 10] § 152°6 | 152-6 | 132-6 | 104-9 | 145-9} 160 
154 ro” Se 0 08 5 pS: Peres: ee Ds Re RD a ES | 
168 | 1 40; 0 10} 3 is | 14 | 5S | 16 i ee) 
182 | 1 50) 0 10) = 161 | 1537] 1447} 98 | 152-7 | 161-0 
196 2 00 0 10 a ee aes SSS eS a et EE es eee 
210 | 2 12) 0 2) = 19 20 | 2i 22 | 93 | 94. 
224), 2 24) 0 12) 2 160-7 | 160-7 | 119-2] 133 | 175 | 181-2 
eam; |, .2)38)|. 0:02 1-5 
252 2 54] 0 18/ & | 
266 3 08| O 14 me Average weight each piece would sustain, 
2s0 | 3 30] 0 a2] * 148-44 Ib. 
294 3 48/ 0 18 Mean of the greatest weight each piece bore, 
308 4 30 0 42 274°3 Ib, 
322 5 30; 1 00 The average time that each piece was under 
329 6 00| 0 30 trial was 8’ 42”, 
336 7 00} 1 00 
181°2 Mean 
Description of the Apparatus for trying Experiments on the 
Strength of Timber. (Plate LXV.) 
The pieces of wood which were the subjects of these experiments 
were fixed so as to be firmly held by one extremity, whilst a load 
was applied at the other, sufficient in the first instance to bend it; 
and the weight was gradually increased till the piece was broken ; 
the degrees of curvature which the different accessions of weight 
produced were noted by means of a divided arch attached to the 
extremity of the piece. 
To fasten the piece firmly in its position, a beam of oak, A A, 
(Fig. 1) one foot square was fixed vertically, and firmly secured 
between the floor and the ceiling. In the middle of this, at B, was 
amortice, six inches by two inches, to receive the end of the piece 
of wood, B D, which was firmly secured by driving in two wedges, 
a, l, from opposite sides, so as to hold it fast down upon the lower 
side of the mortice. The piece, B D, was planed true to its in- 
tended dimensions; and for the purpose of applying the load, as 
well as to ascertain the degree of flexure, an arch, E, was fastened 
on at the extremity, by a tenant at the end of the piece being in- 
serted, and keyed into a mortice made through the middle of the 
arch ; and to keep it firm, a short piece of rope, e, was made fast 
Vor, 1X. N° IV. U , 
