542 Progress in Science. (October, 
of its supply through a conduit or feeder from the Muddock River 
and one-fourth in the same manner from the Moneyscalp river. The 
water is impounded to a depth of 35 feet above the old lake which existed 
there, and can be drawn off to a depth of 38} feet below top water. The area 
of the old lake was 93 acres, and that of the present reservoir 250 acres, and 
the capacity 270 million cubic feet. The embankments are substantially 
constructed, and protected against the wash of the water by strong stone 
pitching. An important and most successful speciality in their construction 
was the use of peat as a supplementary aid to the puddle. The water is 
discharged through two 18-inch iron pipes, secured in a culvert built in the 
solid ground beneath the main embankment, and is conducted by an open 
channel to a point about 1 mile down stream from where the supply is lifted. 
The water from the reservoir reaches the Bann after flowing down the Muddock 
for 6 miles. From the mouth of the Muddock to the weir, where the surplus 
water of the Bann is lifted for the Corbet reservoir, there is about 4o feet of 
unoccupied, and 74 feet of occupied, fallonthe Bann. At this weir the care- 
taker daily measures the quantity of water coming down the river, and thereby 
regulates the amount to be supplemented by the reservoirs. The channel of 
the feeder from this weir to the Corbet reservoir is about a mile long, and 
wide enough to take in considerable floods. The area of the reservoiris about 
70 acres when the water is at top level, or 114 feet above discharge outlet. 
The water is discharged through small iron sluices into a conduit communica- 
ting with the river. The cost of these works has been about £30,000. 
In the paper upon lighthouse illuminations the author observed that in 
order, under present arrangements, to make out with certainty what any 
observed light is, it is necessary that the master of the vessel shall first 
ascertain the position of his own ship. In many cases this cannot be done 
even in short voyages, but after a long voyage, and with but few opportunities 
for making correct observations, errors of many miles may occur in a ship’s 
reckonings. Every year the accounts of shipwrecks show the fatal results 
arising from the mistake of one light for another light many miles away: the 
signal which properly interpreted should have preserved the mariner from 
danger, misinterpreted becomes the false guide which lures him to destrudtion. 
Even coloured lights do not afford the required protection, but what is required 
is that each light should unmistakably declare its own identity ; and the plan 
for effecting this, which was first proposed by Charles Babbage, in 1851, and 
has recently been perfected by Sir William Thomson, is that each lighthouse 
shall exhibit from sunset to sunrise a certain definite series of eclipses repre- 
senting one of the letters of what is known in telegraphy as the Morse 
alphabet. This method has recently been adopted by the Harbour Commis- 
sioners of Belfast for the light on the Holywood Bank, where, by the use of 
three shutters, or screens, two short eclipses and one long eclipse are given, 
corresponding to the letter U in the Morse alphabet, and the system will 
therefore receive a fair trial. 
The majority of the papers read before the Iron and Steel Institute at their 
meeting at Barrow-in-Furness belonged more to geology than engineering, 
but two of them may be classed under the latter heading—one being a paper 
by Mr. Robert Luthy, ‘“‘On Valves Suitable for Working Hydraulic Machi- 
nery ;”’ and the other, by Mr. T. Wrightson, of Stockton-on-Tees, ‘‘On a New 
Form of Wagon Drop for Blast-Furnaces.”’ 
In the former paper it was explained that under high pressures the old- 
fashioned taper, or circular, valves are not reliable; brass slide valves of the 
usual D pattern, similar to steam-engine slide valves, do very well for smaller 
sizes, and if their working faces are made of hard metal they last a consider- 
able time; but for the larger sizes the friction becomes so great that, in order 
to work them by hand, a very great leverage has to be employed, and this 
prevents the valves being opened or closed quickly enough. Mitred plug 
valves are used in some places, but they are complicated and expensive, and 
require a great deal of room. The foregoing arrangements of valve have all 
metal faces, but recently valves have been introduced in which the peculiar 
properties of the leather collars for making hydraulic joints have been applied 
