TRANSACTIONS OF SECTION G. 811 



one machine was overpowered by the volume of sewage, the second machine would 

 come into action. By this method power could be transmitted more economically 

 than by any other mode at present in use, and with the additional advantage that 

 the water after use can be applied for flushing purposes. 



4. On the Birmingham, Tame, and Rea District Drainage Board. 

 By W. S. Till.— See Reports, p. 499. 



MONDAY, SEPTEMBER 6. 



The following Papers were read : — 



1. Electric Illumination of Lighthouses. 

 By J. HoPKiNSON, M.A., D.Sc, F.B.S. 



The paper related to the cost of the electric light in lighthouses, and suggested a 

 method of reducing the same. It has hitherto been supposed that it was not pos- 

 sible to establish and maintain an electric lighthouse at anything like the expense 

 of a first-class light in which paraffine is used in the ordinary way. The high 

 expense of the electric light arises in a great measure from the fact that the 

 machinery is placed at a distance from the lantern, so that two attendants are 

 always required on duty. The author suggested that a small gas-engine and dynamo 

 machine should be placed in the room immediately below the lantern, and arrange- 

 ments should be made whereby the lightkeeper, whether he is in the lantern or 

 in the engine-room, could ascertain at a glance whether the arc is in its proper 

 position. The attendance on the lamp, rotating apparatus of the lens (if a revolv- 

 ing light), engine and dynamo would be easy when the whole is brought together 

 so as to be under observation at once ; in fact, the gas-engine, dynamo, and lamp 

 would constitute together a gas-burner, which, though consisting- of many parts, is 

 automatic throughout, and when at work requires nothing but the constant 

 presence of a custodian, exactly as a gas lamp in a lighthouse requires a custodian 

 as a guarantee against failure. 



The plant would consist of a Dowson gas-producing apparatus and gas-holder, 

 the generator and superheater being in duplicate, each capable of making 1,200 

 feet of gas per hour, the gas-bolder having a capacity of 3,000 cubic feet ; an 

 eight-horse (nominal) Otto gas-engine and series-wound dynamo machine, placed 

 in a room near the base of the tower and copper conductors to the lantern, 

 the dynamo having magnet coils divided into sections so as to supply a small 

 current when required ; a one-horse (nominal) Otto gas-engine and dynamo machine, 

 placed in the room immediately beneath the lantern floor, with gas-pipe from the 

 gas-holder ; one spare armature ; the electric lamps to receive either carbons of 

 25 mm. or any lesser size, with complete adjustments for accurate focussing ; one 

 parafiine lamp as a stand-by ; an optical apparatus of the second order, 70 cms. 

 focal distance. The cost of this apparatus would depend upon the character of the 

 light it was intended to exhibit. Provision would be made in the optical apparatus 

 for giving the horizontal and vertical divergence desired by the methods suc- 

 cessfully used in the lighthouses of Macquarie and Tino. Two focussing prisms 

 would be fixed to form magnified images of the arc on pieces of obscured glass, let 

 into the pedestal floor, so that the keeper, whether in the lantern or in the engine- 

 room, could see at a glance the state of the arc, and observe whether it is of proper 

 length, with the carbons in line, whether it is of exactly the right height and in the 

 centre of the apparatus. An error of one millimetre would be glaringly apparent, 

 and call for immediate adjustment, although its effect would only be a displace- 



' Published in extenso in the Electrical Review, Oct. 8, and the Electrician, 

 Oct. 29. 



