ON IMPROVEMENTS IN ELECTRIC SAFETY LAMPS. 499 



comparison wire. "With the single wire arrangement, under the same 

 atmospheric conditions, the wire would glow for an instant with extra 

 brightness, and then, after the small quantity of enclosed fire-damp is 

 consumed, would die down to normal redness. 



The third form of indicator acts upon a different principle. In it 

 there is a platinum wire within a small tube, and the means of turning 

 on the current from the lamp battery to heat the wire, as before ; but here 

 the hot wire is employed only to effect the combustion of any fire-damp 

 that may be present, with a view to the production of a partial vacuum 

 resulting from the condensation of the watery vapour of the burnt gases. 

 The degree of vacuum or shrinkage is shown by the rise of liquid in an 

 adjacent gauge-tube, and from this the exact percentage of fire-damp 

 present in the air may be ascertained. This form of test is also, and 

 necessarily, made in a closed vessel. The hot wire is completely cut off 

 from contact with the outer air. 



I think it will appear to the Section that I have produced a miner's 

 lamp having the advantage of absolute safety, and which is, at once, more 

 efficient and more economical than any other miner's lamp yet con- 

 structed. 



On the Birmingham, Tame, and Rea Blstrict Drainage. 

 By William Till. 



[A communication ordered by the General Committee to be printed in exfenso 



among the Eeports.] 



The author in submitting this paper begs to state that he has not 

 entered into any discussion of the relative merits of the various systems 

 of sewage purification now in operation, nor has he advanced any theory 

 of his own in relation thereto, but has confined himself to a practical and 

 historical account of the work of the Birmingham, Tame, and Rea District 

 Drainage Board, merely adding from time to time such remarks as seemed 

 needful for the proper explanation of the subject under consideration. 



In giving an account of the formation and work of the Drainage 

 Board, the works of sewage purification previously undertaken by the 

 Corporation of Birmingham form so important a part that any general 

 description of the Drainage Board would be incomplete without some 

 reference thereto ; but inasmuch as the efforts of the Birmingham Cor- 

 poration to deal with the sewage difficulty have been so prominently 

 before the various bodies interested in sanitary work, both from the pro- 

 ceedings in Parliament and from several published statements, it has not 

 been thought necessary to make further allusion thereto than may be 

 required for giving a complete history of the position and work of the 

 Board. 



It may perhaps be desirable to glance briefly, in the first instance, at 

 the sanitary condition of the district generally prior to the formation of 

 the Board, with a view of setting forth more clearly the advantages the 

 various authorities now comprising the Board were intended to derive 

 from their union. 



The borough of Birmiagham, together with the towns of Walsall, West 



K K 2 



