duced, were prepared for laying in the new minefield in the Straits
of Dover. _In the fourth quarter of the year a total of 10,389 mines was
laid in the Heligoland Bight and in the Straits of Dover._

During this last quarter delivery of "H" pattern mines was as follows:
In October 2,350, November 5,300, December 4,800; total 12,450. So that
it will be seen that the mines were laid as fast as delivery was made.

The great increase in projected minelaying operations during the year
1917 made it necessary also to add considerably to the number of
minelaying vessels.

In January, 1917, the only vessels equipped for this service were four
merchant ships and the Flotilla Leader _Abdiel_, with a total minelaying
capacity of some 1,200 mines per trip. It was not advisable to carry out
minelaying operations in enemy waters during the period near full moon
owing to the liability of the minelayers being seen by patrol craft.
Under such conditions the position of the minefield would be known to
the enemy. As the operation of placing the mines on board occupied
several days, it was not passible to depend on an average of more than
three operations per ship per month from the larger minelayers.
Consequently, with the intended policy in view, it was obvious that more
minelayers must be provided.

It was inadvisable to use merchant ships, since every vessel was
urgently required for trade or transport purposes, and the alternative
was to fit men-of-war for minelaying. The only old vessels of this type
suitable for mining in enemy waters were ships of the "Ariadne" class,
and although their machinery was not too reliable, two of these vessels
that were seaworthy were converted to minelayers. In addition a number
of the older light cruisers were fitted with portable rails on which
mines could be carried when minelaying operations were contemplated, in
place of a portion of the armament which could be removed; a flotilla of
destroyers, with some further flotilla leaders, were also fitted out as
minelayers, and several additional submarines were fitted for this
purpose.

For a projected special scheme of minelaying in enemy waters a number of
lighters were ordered, and some of the motor launches and coastal motor
boats were fitted out and utilized for mining operations on the Belgian
coast towards the end of 1917.

By the end of that year 12 light cruisers, 12 destroyers and flotilla
leaders and 5 submarines had been fitted for mine