rking costs and a proportion of the
charge for actual superintendence, but no allowance for interest on
capital cost or depreciation. On an average, 20% of the sand and mud
that are raised escapes over the side of the vessel. Mr Lyster has,
however, to a considerable extent overcome this difficulty by a
special arrangement added to the hoppers (see _Proc. Inst. C.E._ vol.
188).

At the Engineering Conference, 1907, Mr Lyster read a note in which he
stated that the total quantity of material removed from the bar of the
Mersey, from the Crosby channel, and from other points of the main
channel by the "G. B. Crow" and "Brancker" suction dredgers amounted
to 108,675,570 tons up to the 1st of May 1907. "In the note of 1899
(he added) it was pointed out that the Mersey was a striking instance
of the improvement of a river by dredging rather than by permanent
works, and the economy of the system as well as the advantage which
its elasticity and adaptability to varying circumstances permit, was
pointed out.... The most recent experience, which has resulted in the
adoption of the proposal to revet the Taylor's bank, indicates that
the dredging method has its limitations and cannot provide for every
contingency which is likely to arise; at the same time, the utility
and economy of the dredging system is in no way diminished.... Having
regard to the ever-increasing size of vessels, a scheme for new docks
and entrances on a very large scale received the authority of
parliament during the session of 1905-1906 In this scheme it was
considered necessary to make provision for vessels of 1000 ft. in
length and 40 ft. in draught, and having regard to this prospective
growth of vessels it has been determined still further to deepen and
improve the outer channel of the Mersey. No fixed measure of
improvement has been decided on, but after careful survey of existing
conditions and a comparison with probable requirements, it has been
determined to construct a dredger of 10,000 tons capacity, provided
with pumping power equivalent to about three times that of any
existing dredgers. By the use of this vessel it is anticipated that it
will be possible to deal with very much larger quantities of sand at a
cheaper rate, and to 10 ft. greater depth than the existing plant
permits."

The vessel in question was launched on the Mersey from the yard of
Messrs Cammell, Laird &