158 REPORT—1857. 
passed over the platform of this bridge without the slightest undulatory or 
oscillating motion having been produced. 
We are hence enabled to infer, without looking to improvements in detail, 
which will naturally be introduced, that a platform so constructed and so 
suspended as the one at Kieff, is capable of sustaining the passage of railway 
trains at a moderate velocity, and within a reasonable cost of construction ; 
and taking the example of the wire bridge in America, and of this wrought- 
iron chain bridge in Russia, it may be legitimately concluded, that the 
adapting of suspension bridges to railway purposes is perfectly practicable. 
The extent to which this application may be made can scarcely be defined 
@ priort, but the writer ventures, from his own experience, to state his 
opinion, that where the span of the required bridge must exceed 300 feet, 
the suspension principle should be adopted for the sake of economy. 
It would be extending these observations far beyond the bounds assigned 
to such meetings as these, to go further into the details, and therefore, how- 
ever tempting the opportunity, we must abstain from entering upon the 
subject of the modern mode of obtaining foundations and forming river- 
piers, which mode would greatly influence any selection between a fixed or 
a suspension bridge. Neither must we even touch upon the choice between 
the wire-rope and the wrought-iron plate chain, as the means of suspending 
the platform, though it is obvious that where the span becomes very large, 
the superior lightness of the wire is a great inducement to decide the pre- 
ference for it over the wrought iron. 
The proportion between the chord and the versed sine of the curve of the 
suspending chain is another point of the highest interest, as relating to the 
questions of more or less oscillation, and of increase or decrease in the 
amount of tension, as this proportion varies. 
It is sufficient to have brought the general subject of the practicability of 
adapting suspension bridges to sustain the passage of railway trains before 
the Mechanical Section of the British Association; and it is to be hoped 
that this opportunity will not pass away without engineers and the other 
scientific and practical men now assembled, bringing their judgement and 
experience to an examination of this very important question. 
On Electro-Chemistry. By Professor W. A. Mituer, V.D., F.R.S: 
In reporting upon the recent progress of electro-chemical research, the 
author stated that the inquiries made of late years in the field of electro- 
chemistry were characterized rather by modifications of the laws previously 
admitted, than by any fundamental additions to the existing stock of know- 
ledge upon the subject. 
Faraday’s observations on the exceptional conducting power of solid sul- 
phide of silver, and one or two ether substances when heated, had been 
traced, by the researches of Beetz and Hittorf, to true electrolytic decompo- 
sition, which is rendered possible by the somewhat viscous condition pro- 
duced by heating these bodies. The true electrolytic nature of the decompo- 
sition was proved, first by the rise in conducting power, oceasioned by rise 
of temperature (whereas in metals the effect is exactly the reverse); and 
secondly by the effects of polarization observed upon the electrodes between 
which such bodies are placed. 
Allusion was then made to the experiments by Bunsen on the insulation 
Ver we " 
