780 KEPOKT— 1881. 



7. On the Relative Value of Incandescent Electric Lights. 

 By J. N. Shoolbeed, G.E., F.G.S. 



8. On the Society of Arts Patent Bill. 

 By Sir F. J. Beamwell, M.I.C.E., F.B.S. 



WEDNESDAY, SEPTEMBER 7. 



The following Papers were read : — 



1. On Coal and the Abatement of SmoTce in Large Towns. 

 By W. R. B. Coles. 



2. On British Shipping and the Tonnage Laws. 

 By Captain Bedford Pim, B.N. 



3. On the Pressure of Wind upon a Fixed Plane Surface, 

 By Thomas Hawkslet, C.T<j., F.B.S. — See Reports, p. 480. 



4. On a New Form of Lightning Conductor, which can he easily tested. 



By Samuel Vtle. 



Last year a paper was read before this Section of the British Association, draw- 

 ing special attention to the great damage done to life and property by lightning, 

 and pointing out the need that existed of periodically testing and inspecting 

 lightning conductors, with a view to their being always liept in an efficient condi- 

 tion. There is, however, very great difficulty in the present method of testing 

 conductors, it being a necessary preliminary to such test that some one be found 

 vsith nerve and sldll enough to carry a testing wire from the gi'ound and connect it 

 metalhcally with the top of the conductor. The electrician, having the other end of 

 the wire below, is then in a position to commence Ms test. Where conductors are 

 attached to lofty spires or high chimneys, there is both cost and danger, which 

 is probably the reason why so few conductors are ever tested. This neglect to 

 ascertain their condition leads to deterioration and ultimate danger, and it is more 

 than probable fosters a widely extended belief that conductors are comparatively 

 useless. 



Recognising this difficulty in the method of testing, and noticing the emphatic 

 utterances of scientific men as to the absolute necessity of testing lightning con- 

 ductors, the author was led last year to devise a new form, which is now exhibited. 



It consists of a copper cable carrying an insulated wire as its core, which wire 

 being metallically connected with the outer cable at the top, offers a ready means of 

 testing its condition at any time without any of the difficulty hitherto experienced 

 in testing conductors. 



Having then a wire always connected to the top of the conductor, a test can be 

 taken when desired. This can be accomplished either on the tangent, balance, or 

 differential principles, either of which will enable the resistance of the conductor to 

 be ascertained. The author had adopted the latter method, the galvanometer being 

 fitted with three keys — A, B, and C. By depressing key A on the left hand a 

 deflection of the galvanometer needle takes place by reason of the passage of a 

 current from the battery through one coil of the galvanometer to the insulated wire 



