These cut plants may be laid in rows on the ground to wilt, or spitted on long rods or laths supported on trestles, or placed on special drying racks.
The needles are put in place one by one against the raised frames, or trestles, by a derrick on a barge lifting them by their ring, whilst a man on the foot-bridge, taking hold of the eye at the top, arranges them in position close together.
A rectangular trough of boards, whose dimensions depend chiefly on the size of the planks available, is set up on the higher part of the ground at one side of the claim to be worked, upon trestles or piers of rough stone-work, at such an inclination that the stream may carry off all but the largest stones, which are kept back by a grating of boards about 2 in.
(t) In erection on staging, the materials available determine the character of the staging; stacks of timber, earth banks, or builtup staging of piles and trestles have all been employed, also iron staging, which can be rapidly erected and moved from site to site.
The trestles of this weir are, as usual, hinged to the apron, so that in flood-time they can be completely lowered into a recess across the apron by means of chains actuated by a winch, leaving the channel perfectly open for the discharge of floods and for the passage of vessels when the lock is submerged.
Whereas, however, ordinary frames placed nearer together than their height overlap one another when lowered on to the apron, the trestles of the Louisa weir lie clear of each other quite flat on the apron.
Or by pulling the props clear of their shoes by chains fastened to the bottom of the shutters; the unsupported trestles and shutters fall flat on the apron on the top of the props, as shown by dotted lines in fig.
The weir is raised again by pulling up the shutters to a horizontal position by their bottom chains from a special boat, or from a foot-bridge on movable frames, together with their trestles and the props which are replaced in their shoes.