770 REPORT — 1901. 



Accordingly an apparatus was devised for remedying the evil. It vsras so 

 successful that the turbine would go for a whole day without attention and 

 without diminution of output from the above cause. 



The apparatus consists of a cylinder of wire gauze, of 4 feet diameter and 

 4i feet height, set in an opening in a vertical diaphragm extending across the 

 supply drain and revolving twice in a minute or so round a vertical axis. The 

 current flows through the gauze cylinder in a horizontal direction. The leaves, 

 carried down with the current, attach themselves under pressure of the stream, 

 are carried round till they reach the diaphragm, which on that side is double, 

 with an intervening space of some ten inches, which is connected with the tail- 

 race ; and at this point, the current through the gauze being reversed, the leaves 

 are detached and are carried by a portion of the water towards the tail-race. 

 Four or five per cent, of the supply is ample for conveying the leaves ; probably 

 much less would suffice. A very few leaves get past and on to the screen, but so 

 few til at they give no trouble. 



The apparatus has also been constructed of the disc form, and also as a 

 cylinder on a vertical axis, the water entering all round, except along one vertical 

 section connected with the tail-race as before, and bearing vertically downwards 

 round the axis ; but only as working models, and on this scale they are even more 

 effectual in their action. But there seemed no sufficient reason for modifying the 

 full-sized apparatus, which has now been in action for nearly a year, and has given 

 complete satisfaction. 



SATURDAY, SEPTEMBER 14. 



Tlie Section did not meet. 



MONDAY, SEPTEMBER 16, 



The following Papers were read :— 



1. The Protection of Buildings from Lightning. 

 By KiLLINGWORTH HEDGES, M.Inst.C.E., M.I.E.E. 



The last time this subject was brought before this Association was at the Bath 

 meetino- in 1888, when a joint discussion of Sections A and G was held ; but there 

 has been no official report as to the effect of lightning stroke upon buildings 

 protected by conductors since the Lightning Rod Conference of 1882. Interest in 

 the subject has been again revived, first, by the Electro-Technische Verein of 

 Berlin, who have this year published a set of rules ; and secondly, by the 

 establishment in this country of the Lightning Research Committee, organised 

 jointly by the Royal Institute of British Architects and the Surveyors' Institute. 



The author compares Continental and American practice, and gives an account 

 of his rearrangement of the system used at St. Paul's Cathedral, where the 

 conductors, erected as recently as 1872, were found to be totally inefficient, both as 

 regards the conductivity of the joints and the resistance of the earth connections. 

 In the plan recommended, both for this installation and for the more recent one at 

 "Westminster Abbey, the number of ordinary conductors from air to earth has 

 been greatly increased, and, besides these, horizontal cables are run on the ridges 

 of the roofs and in other prominent positions so as to encircle the building, being 

 interconnected to the vertical conductors wherever they cross one another. The 

 horizontal cables are furnished at intervals with aigrettes, or spikes, which are 

 invisible from the ground level, and are designed to give many points of 

 discharge. At the same time they, in conjunction with the cables, would receive 



