4 TECHNOLOGY. 
Sf (jig. 5), and the spaces ce paved with small pebbles, on which the horses 
have a safer hold. Sometimes long stone sleepers are employed for the 
wheel-ways, jointed together as seen at jigs. 7 and 8. Another mode of 
joining the stretchers, by Mathews, is shown in jig. 9, by which not 
only the lateral displacement but also the lifting of the ends is to be pre- 
vented. ‘This is effected by the introduction of a key-stone, d, which may 
either be shaped as in jig. 10, cde, or else as in jig. 11, cde. 
In order to avoid the disagreeable noise and diminish the dust attendant 
on stone pavements, it was proposed in England and France to use instead 
of the paving-stones blocks of wood of equal size, placed with the transverse 
section of the fibres on the surface. 
This idea was favorably received, and trials were made by paving whole 
streets in this manner, on which, however, many drawbacks and imperfec- 
tions became apparent, the most important among which were the great 
cost and the action of moisture, which by swelling the wooden blocks 
deranged their position and dle firaptord the pavement. On this account 
en pavements have gradually disappeared, but they are frequently 
applied in passages, covered ways, and stables, where they are found to 
answer very well. There are many different modes of constructing wooden 
pavements, and we will proceed to consider some of them. 
The simplest kind of wooden pavement consists of cubical blocks of wood 
placed so as to break joints on an even and firm foundation of sand, and 
firmly pressed together by a curb-frame ; but such a pavement is too much 
affected by changes of temperature and moisture to remain in order long, 
and with any unequal yielding in the foundation it will become uneven. 
It was therefore proposed so to shape and arrange the blocks as to support 
each other, similar to the voussoirs of an arch. Of this kind is the pave- 
ment represented in pl. 1, fig. 216’. It consists of blocks of wood (jig. 21 a) 
the tops of which are regular hexagons, as the dotted lines 0)’ (fig. 21 a) 
show, while the lower sides are irregular hexagons of three long and three 
short sides, a@and a’. Hig. 21a shows how according to this construction 
the sides of the blocks form warped surfaces, which, when the blocks are 
arranged as in jig. 210, will hold and lock them in such a manner that no 
single one can be removed. Grooves are cut into the upper surface in order 
to afford a safe footing for the horses. 
Arranged on a similar plan is the construction of Laves of Hanover. 
Fig. 13 represents a walk for foot passengers; jig. 12, a carriage-way ; 
jig. 14 is a cross-section and jig. 15 a longitudinal one of the latter. Here 
the wooden blocks rest on the cross-sill ¢ and the longitudinal beams or 
sleepers 4 and 6; their upper surfaces are regular squares, while the sides 
are cut obliquely in different forms, and in such a manner that the several 
prisms form, as it were, voussoirs of a flat arch, which are held immovably 
against each other by a key-prism. The latter is fastened by screw-bolts to 
the sleepers. When the pavement gets wet and the prisms swell, the pres- 
sure which they exert upon each other, and which otherwise raises the 
pavement in the form of an arch, is thus directed downwards, in which 
direction no displacement is possible. 
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