December 11, 1885.] 



SCIENCE. 



13 



communicated indirectly through media. Web- 

 ster and other lexicographers use the terms synony- 

 mously. Dr. Himt thinks both terms should 

 be discarded, and the word ' communicable ' sub- 

 stituted. The term 'zymotic' as applied by Tarr, 

 received its impetus from Liebig's ' Chemistry of 

 agriculture ; ' but there is now, with our present 

 views, no use in retaining it. ' Epidemic,' as 

 applied to those diseases which affect large bodies 

 of the people, as nations ; ' endemic,' those which 

 affect localities ; and 'sporadic,' which occur iso- 

 lated, — are used with various meanings. The term 

 ' sporadic ' should be abandoned. In concluding, 

 he thought the number of terms now used in the 

 nomenclature of disease could with great advan- 

 tage to science be reduced at least one-half. 



little more resistance is experienced than in haul- 

 ing a similar train along a rigid road. 



The automatic governing of the speed of the 

 train is effected in two ways, — first, there is a 

 governor attached to each motor, which interrupts 

 the electric circuit, and cuts off the jjfjwer when 

 the speed becomes too high ; secondly, there is a 

 brake which is brought into action should the 

 speed attain a still higher value. To avoid the 

 formation of a permanent electric arc when the 

 circuit is broken, the governor (fig. 2j is so ar- 

 ranged that the diverging weights are in unstable 

 equilibrium between two stops : they flly out at 

 about 1,700 revolutions per minute of the motor, 

 and fly back at about 1,600. When the circuit is 

 closed, the current is conveyed across the metallic 





Fig. 1. 



telpherage: 



The experimental telpherage train at Glynde, 

 England, which was described in Science of Nov. 

 13, consists of an electric locomotive, seen in fig. 1 

 at about the middle of the train, and propeUed by 

 the electromotor M (fig. 4), and ten skeps, or 

 buckets, which hang by their travelling-wheels 

 from the steel line. Each skep weighs 101 lbs., 

 and carries 250 to 300 lbs. of dry clay ; and by 

 distributing these evenly, and somewhat widely 

 apart, the strain on the steel hne is smaU, although 

 the total weight of the train and clay is about two 

 tons ; also, as equal weights are simultaneously 

 ascending and descending similar inclines on the 

 several spans, the effect of the sag on the mechan- 

 ical resistance of the train is neutralized, and 

 1 Condensed from Nature of Nov. 5, 



contact at C. When the weights TF TF fly out, tliis 

 contact is first broken, but no spark occurs, be- 

 cause a connection of small resistance is con- 

 tinued at B between the piece of carbon and a 

 piece of steel, which, being pressed out by a spring, 

 follows the carbon for a short distance as the arm 

 A begins to fly out. This contact is next broken, 

 producing an electric arc ; which, however, is in- 

 stantly extinguished by the lever A flying out t o 

 the dotted position. The brake is shovrQ on fig. 3, 

 and consists simply of a paii' of weights, TT'' W, 

 which, at a limiting speed greater than 1,700 revo- 

 lutions per minute of the motor, jDress the brake- 

 blocks B B against the rim C C, and inti'oduce the 

 necessary amount of retarding friction. In 

 practice, however, with the gradients such as exist 

 at Glynde, and which do not exceed 1 in 13, the 



