178 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



JUNB, 



EXPERIMENTS ON THE STRENGTH OF TIMBER AND IRON. 

 We have been favoured with the following interesting experiments 

 on the strength of wood and iron, by Mr. Moxham, of Neath ; they 

 were made in the presence of a party of gentlemen for the purpose of 

 illustrating the laws of increased strength, &c., in relation to increased 

 dimensions ; they are important for the purpose of testing the formulae 

 of Tredgold, and likewise the Tables given in the fourth volume of 

 the Journal, pages 79 to 82. 



American Yellow Pine Tiubib. 



Experiments on bars of American yellow pine, straight-grained, dry, and 



free from knots. 



Suspended Deflection, 



weiuht. 



Experiment 1.— Bar I in. square, and 5 ft. 

 between bearings, on which it rested loosely, the 

 weight being suspended from the middle. 



ri6 lb. 

 24 

 32 

 34 

 36 

 38 

 40 



1-5 in. 



2.25 



300 



3-31 



3.81 



4-44 



4-75 



In about 5 minutes this increased to 6-25 in., after which the piece broke 

 with the same weight : the first symptoms of fracture were shown by cracks 

 indicating a compression, from the top edge down to about the middle. 



r32 lb. -S/S in, 



Exp. 2. — Yellow pine, as above, 5 ft. long, 

 Ij in. deep, and J wide. 



48 



64 



96 



128 



136 



•53 

 •75 



1-12 



1-5 



1-69 



144 [increased to 2' 



■'..'', 



152 [ditto 



160 2-62 



[and incr. to 2-87 



! 166 3-75 



3J in. was the greatest measured deflection, and with this weight the bar 

 broke, the first signs of giving way being near the top. When broken, the 

 fracture was comparatively smooth at the top and about § of the way down, 

 from compression ; while about i at the bottom was ragged from the fibres 

 being violently torn apart. 



0-5 in. 



1-06 



r rx , ri2Blb. 



Exp. 3.— Yellow pme, as before, 5 ft. long, I 255 



2} in. deep, and J wide. 1 320 broke it. 



The depth which appeared to have been compressed and that which was 

 extended were nearly the same as in the last experiment. 



Exp. 4.— Yellow pine, 5 ft. long, triangular 32 

 bar, the edge or vertex being down, IJ in. wide J 64 

 on the base of the angle, and li in. deep in the | 96 

 centre. v 



16 lb. 



I 104 

 ^112 



0-19 in. 



0-43 



1-03 



1-75 



2- 



2 broke it. 



,16 lb. 



' 32 

 Exp. 5.— Yellow pine, 5 ft. long, same section I g^ 

 as last experiment, the edge or vertex of the-j gg 

 angle placed upwards. A [increased to 2-62 



LlOO & broke it 3- 



0-31 in. 



0.57 



110 



2-37 



Exp. 6.— Yellow pine, 5 ft. long, IJ in. wide, 

 and J deep. 



^16 lb. 

 32 

 64 

 72 

 80 



[and incr. to 

 82 



•75 in. 

 1-5 

 30 

 3-94 

 5-31 

 60 

 7-25 



'- finer, to 7-81,4 broke. 

 Cast Iron. 

 The iron in this and the four following experiments was the same, being 

 tlie best Welsh cold-blast iron, melted in an air furnace. Half the weight 

 of the bar to be added to the weight suspended from the middle. 



Exp. 7.— Cast iron bar, 5 ft. long between ril2 lb. 

 bearings, weight suspended from the middle, and I 168 

 ends loose as before ; bar J in. and ^ square, or 1 224 

 •78 in. ; weight of bar between bearings 9 lb. \ji'jl 



ril2 1b. 



Exp. 8.— Same length as above, and exact 

 section -40 in. wide and 1-55 in. deep; weight 

 9Jlo. 



224 

 336 

 448 

 604 

 532 

 ^560 



1-375 in. 

 1-81 

 2-69 

 [3-22,&brokeit. 

 0-125 in. 

 0-31 

 0-64 

 0-94 

 1-125 

 119 

 Broke it in 



the weight was suspended being screwed tight, instead of left loose : it 

 broke 2 in. from the middle. 



Exp. 9. — 5 ft. between bear- 

 ings of this section, cast as it 

 was placed in the experiment; 

 weight 101b. 

 . AB = ii. B C = ^, BD = li,l 

 6 and F E=-i% of an inch. 



^112 lb. 



224 



336 



448 



504 



560 



616 

 '-636 broke it. 



016 in. 



-37 



•69 



•94 

 M2 

 1-82 

 1-5 



•rii 



'22 



S I 00 



2 1b. 

 24 



Exp. 10. — Bar cast from same pattern as above, 

 but cast, and placed in the experiment with the 

 thin part down, the reverse of experiment 9. This j ^jg 

 bar weighed 5 lb. hghter than the above, though | j^j 

 there was no perceptible diifeienoe in the section, 

 and it was equally sound. 



^112 lb 

 224 

 Exp. 11. — Bar 5 ft. between bearings, -^ 



0-42 in. 

 0.67 

 1-00 

 The bar bore this for 

 a few seconds only. 



(•437) in. thick, 2^ (203) in. deep in the mid- 

 dle, and -91 at the bearings, the under side having 

 the same curvature as a parabola, which makes 

 the average depth 1-66 in.; weight of bar be- 

 tween bearings 11 lb. 



0-16 in. 



0-31 



0-43 



0-60 



0-75 



0-92 



1-00 



1-07 "1 



1-19 y 



336 



448 



560 



672 



728 



784 



840 

 "-868 broke it. J 



* 3 in. from the middle on one side, and 16 in. from the middle on the 

 opposite side ; showing that there was more than a proportionate strength 

 at the ends of the bar. 



In Exp. 13 the bar was straight at top and hollowed out on the under side, 

 having a section at the middle of H i"- deep, and ^ in. thick, and at the 

 ends of 2^ in. and the same thickness. It was placed with the straight edge 

 on the top, the ends being loose; and with a weight of 224 lb. + h\ (half weight 

 of bar ) the deflection was 09 in. It was then taken up, and replaced with the 

 curved edge up, the ends still loose; and with 224 lb. + 5i (half weight of 

 bar,) the deflection was 0-94 in. It broke with less than 252 lb., but the 

 quality of iron in this was not quite equal to that in the preceding experi- 

 ments : making allowance for this, we should find its strength not greater, if 

 so great, as that of a bar the same length and thickness, and of a uniform 

 depth of 1-i ill. The weight between bearings was lO.V lb. 



^224 lb. 0-31 in. 



Exp. 14.— Cast iron bar, a part of tlie one 336, 0-47 



broken in experiment 7th, placed 2 ft. 6 in. be- J 448 0-62 



tween bearings; ends loose, &c., as before ;j 504 

 weight of bar 4 lb. between bearuigs. I 560 



Broke in putting on an additional 14 lb. 



0-72 

 0-86 

 0-93 



half a minute. This was probably strengthened by the fastening from which 



MISTAKES AND MISREPRESENTATIONS. 



In speaking of our number for April, 1841, the Bauzeitung has fallen into 

 a conglomeration of blunders, jumbling different articles and subjects together 

 in the oddest manner possible. " Episodes of Plan on Roman Architecture," 

 it savs, " must be passed over by us on account of its length, and because it 

 does' not admit of compression ; and for the same reason so must also Can- 

 didus Noti:en Buck! Fasic. XXV, which paper consists of fragmentary 

 criticisms, and chiefly upon Professor Hosking's lectures." This is a tolerably 

 pretty specimen of the art of blundering by wholesale ! " The Episodes of 

 Plan" and " Roman Architecture " (the latter from the Penny Cyclopedia,) 

 are two distinct articles, several pages apart from each other. As to the 

 " Note-book," again, that Fasciculus is so very far from being chiefly upon 

 Professor Hosking's lectures, that it only incidentally mentions his name m 

 one of the shortest paragraphs, without saying anything of his lectures at 

 all But there does happen to be in the same number an article signed S. L., 

 and headed " Candidus' remarks on the lectures of the Professor of Archi- 

 tecture," meaning not remarks by C. himself, but comiter-remarks in reply 

 to others he had previously made ; nor were those remarks upon the lectures 

 of Professor Hosking, but on the lectures of the Professor of Architecture 

 at the Royal Academv. It will be a mercy if the Bauzeitung should not now 

 go and mistake Professor Brown for Professor CockereU, or jumble all the 

 three Professors together, and compound them into one individual ! 



