( 84 ) 



It is clear that a piece of wood, only a foot lon<, will shew only a small amount of ex- 

 pansion, and that if the wood be very hard, the expansion will be almost imperceptible. To 

 ensure more accurate readings, therefore, and to make the instrument more sensible to the 

 changes in expansion, the construction at fig. III. No. 4, will be useful. Here the indicator a 

 is not fixed to the wood itself, but is attached to the end of a horizontal moveable brass bar 

 b b, which can be fixed by a screw (c). The triangle (d) selves to faoilitate the insertion of 

 the indicator and its end piece at right angles with the experimental wood-staff. I think it 

 would also be well, if in this case a small brass cap were fixed to the end of the wood-staff, as 

 it would ensure greater accuracy in movement. The scale here is not straight, but forms a. 

 circle-segment, of which the centre of the radius rests in the nut at the base of the indicator. 

 This instrument will be worked in precisely the same manner as that represented in Fig. III. No. 

 1, the only difi'erence between the two being that the indicator is placed at right angles to the 

 end of the wood-staff by pushing the horizontal moveable brass bar until it touches the wood. 

 The slightest change in the expansion of the wood in the direction of the end piece which 

 touches the indicator will then be shewn iu an exaggerated degree upon the scale, and will thus 

 render the readings very easy. 



The whole of the wood-testing apparatus as above explained can be constructed in such 

 a manner as to admit of its being taken to pieces after use and tlie separate parts stored into 

 the drawer (fig. I. B) destined for them. This would form a small portable box of only about 

 1| to 2 feet square or oblong. 



A general description of the timber and the results of the experiments made might be 

 most advantageously drawn up at the head-quarters office at Calcutta by one and the same 

 ofiicer, for it is obvious that iu the face of the present vagueness and uncertainty of terras for 

 grain, fibre, colour, texture, density, hardness and cleavage, no uniformity can be looked for, 

 unless a strict terminology is introduced. The terms as used by cabitiet-makers, etc., with 

 which I am however, quite unacquainted, might possibly be used for this purpose. 



. 4. Preservation and keeping of wood-specimens. 



Although collections of woods possibly exist in every Conservator's office, I think such 

 collections are not made upon any uniform plan, and that the shape and sizes of the wood speci- 

 mens vary very much. The plan which I submit is, if I correctly understand, already in 

 force in France,* and would I believe be preferable to the one adopted in India, according to 

 which large pieces or rather parts of logs are selected for these collections. 



A log upwards of three feet in girth may give four sections, each complete in itself, shew- 

 ing heart- wood, sapwood and bark ; or only two sections if it is below three feet in girth, while 

 a log of very small girth would give only a single piece. A log may be cut into complete 

 specimens for a wood collection, somewhat in the manner shewn iu the subjoined sketches. 



* I have seen similar collections with German foresters, who had these book-shaped pieces of wood hollowed 

 out inside, in which were preserved not only the leaves, flowers, etc., of the respective trees, but aJso the insects 

 iujurious to them. 



