By means of an adjustable valve the flow of water can be regulated according to the state of the roads, and, if necessary, a double valve can be inserted, so that either side of the distributor can be at work when only half the width is required, or when passing a carriage or narrow spaces.

The branch pipe is of uniform size, except close to the spreader, where it enlarges in order to avoid friction, and this is assisted by the branch pipe being shaped into a cycloidal curve on each side.

In order to obtain as great a pressure as possible upon the jets of the distributing pipe, and thus to give the side jets a greater trajectory than they otherwise would have, the tank is elevated as high as is consistent with the conditions of draught. At the same time, the distributing pipes are placed as near to the ground as convenient, so that the maximum extent of distribution is obtained, and that with less dust and splashing than in the ordinary system. The holes in the distributing pipe instead of being drilled in straight lines, are on a curved line, which rises along the length of the pipe from the centre towards the ends. This has been found necessary, in order that the distributing pipe may be placed low, and at the same time advantage be taken of the width of the trajectory of the jets.

Comparing the work of one of these vans with that reported upon by Mr. Scott, it is found that the van occupies nine minutes in filling, six minutes in spreading the water, and only three hours and fifteen minutes in travelling to and fro, so that in seven hours it accomplishes as much work as the ordinary water cart effects in ten hours.

In Edinburgh, where a trial of one of these vans took place against one of the old carts, it was found that the van spread the water a width of 20 feet, while the old cart only covered 14 feet; the van conveyed the water 1,731 feet, and the cart only 951 feet. The superficial area watered by one load of the van was 34,620 feet, and by the old system only 13,314 feet. When we consider the time that is lost in travelling to and from the stand pipe, what a large saving this represents in the cost of this work.

Mr. Tomkins, C.E., the surveyor of the important Metropolitan parish of St. George, Hanover Square, has made the following comparative experiments with one of Bayley's vans as against an ordinary cart:—

Contents in Gallons.No. of Loads to cover beat.Total quantity of Water.Time.Difference.Gain per Cent.
Hrs.Mnts.Hrs.Mnts.
Van4505½2475123——
No. 4 Cart22511247515002724½
Van4505½2475138——
No. 9 Cart23711260721003225
Van45062700145——
No. 15 Cart29011319021002519¼
Van45083600215——
No. 19 Cart26017442033011536

This shows a mean gain of 26 per cent. in favour of the van, and the following tables made by an inspector in 1873, showing the actual occupation of the ordinary carts and Bayley's vans during a day's work, are extremely interesting, as showing that while the van is engaged in spreading the water the time of the cart is wasted in travelling to and from the stand posts, and when it is borne in mind also that the van spreads water more widely than the cart, there can be no doubt that a saving of at least 30 per cent. can be effected by the substitution of these vans for the old-fashioned cart.

CARTS.
Filling. Travelling
Full.		Travelling
Empty.		Waiting, &c.Spreading.
H.M.H.M.H.M.H.M.H.M.
Paddington14529158020130
St. Saviour's12921624026129
Strand11123021801713
Kensington4402215700154
Chelsea24411521403516
VANS.
Paddington33319130030
St. Saviour's22014121023258
Strand230125114020223

One of the earliest methods for watering streets, but one which has, I think, almost entirely died out on account principally of the large quantity of water used in the process, was that of allowing the water to run down the channel gutters, ponding it back by means of canvass or leather aprons placed across the gutter, and then spreading the water on to the surface of the street by throwing it with wooden shovels.