Himcpava Mountains. 923i 
«8B. Tus rods which are rectangular prisms twenty-five feet in length, 
and 1z by 13 inch; were meant to be placed in pairs; the two pairs being 
separate, and one remaining fixed, while the other pair should be brought 
forward. ‘To support each pair of rods, nine stands were required, being 
placed at distances of 6 feet. Thus for the four rods, were wanted 
eighteen, and nine to be laid ready for the rods that were to be next brought 
forward, to which adding ten more, five large and five small for unexpected 
inequalities, the total number is thirty-seven. ‘Though this be a large num- 
ber, yet the quickness with which they are constructed, more than makes 
amends, so that where wooden rods are used, I do believe it to be one of the 
most convenient methods of supporting them that I have any knowledge of. 
i 9, Tae rods which formed the pair, were placed interlocking (fig. 4) 
the ends being cut to allow of that arrangement. But the pairs being 
placed separate, so as to allow of having a fixed point on the ground; 
required some means of measuring the distance between them. I adopted 
the same method as that alluded to (art. 4). The fixed or hinder paw 
had attached to their anterior end, a brass cheek projecting + inch beyond 
the wood, to which, it was secured by two screws, passing through the rod, 
and clamped with nuts. The fore pair again had attached to their upper 
surface a brass plate on which a groove was fashioned, a slide moved 
freely in this groove and could be pushed out so as to touch the fore edge 
of the brass cheek belonging to the hinder or fixed pair of rods. The 
quantity being measured by a Nonius. This apparatus is represented 
by fig. 5. | 
VOL. XIV. 3N 
