144: ANNUAL OF SCIENTIFIC DISCOVERY. 



force of magnetic attraction instead of the deflection of the needle as a 

 means of measuring the amount of current circulating. This force was, he 

 said, until we approach the point of magnetic saturation of the iron, strictly- 

 proportioned to the energy of the current under examination. The number 

 of grains thus lifted on the arm of the lever the author proposes to call the 

 practical "value" of the current for telegraphic purposes. The most striking 

 features of this instrument are 1st. The facility of determining the value of 

 currents which do not admit of being tried by the galvanometer. 2nd. The 

 very great range which this instrument has (viz. from unity up to half 

 a million), as well as the deflniteness and accuracy of the results, even the 

 extremes of the register being strictly comparable with each other. 

 3rd. Unlike the degrees upon the galvanometer, these grains of force are 

 units of real "value" and of practical utility, as was shown by a telegraphic 

 instrument hi circuit being worked perfectly by a current of four grains. 

 Referring to the proceedings of the association last year, the author showed 

 that a wire six tunes the length of the Varna and Balaklava wire, if of the 

 same lateral dimensions, would give thirty-six times the retardation, and 

 thirty-six times the slowness of action. If the distinctness of utterance and 

 rapidity of action practicable with the Varna and Balaklava wire are only 

 such as not to be inconvenient, it would be necessary to have a wire of six 

 times the diameter, or better, thirty-six wires of the same dimensions, or a 

 larger number of small wires twisted together, under a gutta-percha covering, 

 to give tolerably convenient action by a submarine cable of six times the 

 length. Although the subject of submarine telegraphy had many points of 

 the highest importance requiring investigation, and to the consideration of 

 which he had been devoting himself recently, Mr. "Whitehouse proposed to 

 confine his remarks on this occasion to the one point indicated in the title, 

 inasmuch as the decision of that one, either favorably or otherwise, would 

 have, on the one hand, the effect of putting a very narrow limit to our pro- 

 gress in telegraphy, or, on the other, of leaving it the most ample scope. He 

 drew a distinction between the mere transmission of a current across the 

 Atlantic (the possibility of which he supposed everybody must admit) and the 

 effectual working of a telegraph at a speed sufficient for " commercial success." 

 The author then gave a description of the apparatus employed in his 

 researches, of the manner hi which the experiments were conducted, and, 

 lastly, of the results obtained. The wires upon which the experiments were 

 made were copper, of No. 16 gauge, very perfectly insulated with gutta- 

 percha spun into two cables, containing three wires of equal length (eighty- 

 three miles), covered with iron wires and coiled in a large tank hi full contact 

 with moist earth, but not submerged. The two cables were subsequently 

 joined together, making a length of 166 miles of cable, containing three 

 wires. In addition to this, in some of the latest experiments he had also the 

 advantage of another length of cable, giving, with the above, an .aggregate of 

 1,020 miles. The instruments, one of which was exhibited, seemed to be of 

 great delicacy, capable of the utmost nicety of adjustment and particularly 

 free from sources of error. The records were all made automatically, by 

 electro-chemical decomposition, on chemically-prepared paper. The observa- 



