•with Remarks on Mr. E. M. Clarke. 3G1 



which magneto-electricity has made since this new path of 

 science was opened by the beautiful and unexpected disco- 

 veries of Faraday, might be misled, from the paper I have 

 alluded to, to believe that the electro-magnetic machine there 

 represented was the invention of the writer, and that the ex- 

 periments there mentioned were for the first time made by its 

 means. No conclusion, however, would be more erroneous. 

 The machine which Mr. Clarke calls his invention, differs from 

 mine only in a slight variation in the situation of its parts, and 

 is in no respect superior to it. The experiments which he 

 states in such a manner as to insinuate that they are capable 

 of being made only by his machine, have every one been lono- 

 since performed with my instrument, and Mr. Clarke has had 

 every opportunity of knowing the truth of this statement. 



Though my machine is tolerably vvell known to the public 

 from its constant exhibition at the Adelaide-street Gallery 

 since August 1833, and my claims as its inventor have been 

 acknowledged by Professors Faraday, Daniell, and Wheat- 

 stone, in papers of theirs published in the Philosophical 

 Transactions, yet as no description of it has yet been published, 

 I will thank you to insert the following in the ensuing Number 

 of the Philosophical Magazine. I think the figures and their 

 explanation will be sufficiently intelligible to enable any work- 

 man to construct a similar ona. 



Fig. 1. is a side view of the magneto-electrical machine; the 

 magnet is placed in a liorizontal position, and consists of 

 twelve plates of the horse-shoe shape firmly fastened together. 

 A vertical wheel communicates motion to a spindle, which 

 carries round with it a cross of soft iron, on the extremities of 

 which are fixed four soft iron cylinders. Fig. 2 represents 

 the spindle and cross before the wire is coiled round the cy- 

 linders: when the wheel is turned, the bases of each of the 

 cylinders pass in succession the two poles of the magnet as 

 closely as possible without actual contact. Fig. 3 represents 

 the side of the armature next to the poles of the magnet; A 

 and B are the soft iron cylinders on which the long wire for 

 giving the shock is coiled ; and C D are the cylinders round 

 which the short wires for giving the spark are coiled : the 

 circular brass plates 1, 2, 3, 4- are for the purpose of keeping 

 the wire on the cylinders. The wires are of copper covered 

 with silk; that for producing the shock is a double wire 400 

 yards in length, and each ^'yth of an inch in diameter; and that 

 for obtaining the spark consists of 20 lengths, each 75 feet 

 long and ^j^th of an inch in thickness, united together at their 

 two extremities. Fig. 4 is vl front view of the armature, show- 

 ing the soft iron cross to which the cylinders carrying the 



Third Series. Vol.9. No. 55. Nov.XSm. 2 U 



