GLEANINGS 
IN 
SCIENCE. 
No. 5.—JI£ay, 1829 . 
I — Results of a Series of Experiments on the Elasticity and transverse 
Strength of different Kinds of Timber. By Captain H. C. Baker, 
Superintendent of Suspension Chain Bridges. 
The experiments of which the results only are below recorded were conducted, as 
nearly as circumstances admitted, with similar apparatus to that used by Mr. Bar- 
low, and described in his Treatise on the Strength and Stress of Timber. The ex- 
treme precision aimed at by Mr. Barlow, for the purpose of establishing a particular 
theory, was neither attainable with the means I had at command now, nor, had it been 
so, would it, after Mr. Barlow’s researches had so satisfactorily established the 
accuracy of his premises, have been attended with any consequences at all commen- 
surate to the difficulty and labour necessary to secure it. 
The specimens, many of them, were obtained from the Commissariat Timber Depdt, 
some very fine ones from the Cossipore Gun Carnage Agency', and others were the 
produce of the Calcutta market ; those of three and two feet in length were, general- 
ly speaking, cut from the sound fragments of tire larger specimens. 
The central deflections of the seven and six feet specimens, were usually noted 
immediately after the application of each 50 lbs. of fresh load, at which time, the set 
taken by each appeared more regular than after some interval had elapsed ; the first 
deflections were commonly recorded with 150 lbs. weight, in some cases with only 
50 lbs.; sometimes the specimen mis turned upon the tressels and subjected to two 
nr more trials, and in a few instances the load was left suspended for many hours, 
deflections being noted at different intervals of time. 
The depth of the neutral axis was occasionally observed, but this has been found 
to vary so very little (being generally 5-8ths of the depth) as to render its insertion in 
the table of results of little practical utility'. 
The direct cohesive strength of the woods having also been subjected to experi- 
ment, the calculation of it from Mr. Barlow’s formula has not been thought neces- 
•ary; but the curious in such investigations arc here presented with abundant mate- 
rials for pursuing the inquiry. 
It is much to be regretted’, that from the circumstances under which most of the 
•pecimens were obtained, so little accurate information respecting the timber 
could be procured. The age, size, time of felling, and circumstances under which 
the trees had been respectively placed subsequently to their being cut down, would 
all have materially' enhanced the value of this statement of results to the man of 
research, but unluckily no such information was accessible ; indeed, in few cases 
was it even precisely known from yvhat part of the timberthe specimen itself was cut 
out, or what number were o if the same trunk. The year of importation, where 
known, has been however inserted. 
The following were the woods experimented on : 
Saul*. Sharea Rabmta. Rox. This timber is too well known to render a length- 
ened description of it requisite, but its value for building purposes does not yet 
* The Saul and Sissooh are obtained from the forests north of the Ganges line, 
between the 25th and 31st N. Lat. 74th and SSth E. Long, but chiefly from the tract 
lying north of Poorneah and Goruckpore. 
