Mr. Faraday's Ninth Series of Researches in Fdectricitij, 301 



of the Hemerohius, Panorpa, Phryganea^ and Ephemeral and par- 

 ticularly in the Musca dornestica, or common house-fly. The paper 

 is accompanied by drawings of the appearances described. 



January 22. — A paper was read, entitled, ** Notes on the Temper- 

 ature of the Air and the Sea, &c., made in a Voyage from England 

 to India, in the Ship Hoogly, Capt. Reeves, in the year 1833." By 

 Alexander Burnes, Esq., F.R.S. 



The observations contained in this communication are recorded in 

 a tabular form, and show that the variations of the temperature of the 

 sea accord very closely with those of the air, in all the latitudes 

 which the author traversed in this voyage. 



A paper was then read, entitled, *• Remarks on certain Statements 

 of Mr. Faraday, contained in the Fourth and Fifth Series of his Expe- 

 rimental Researches in Electricity." By John Davy, M.D., F.R.S. 



Dr. Davy complains that Mr. Faraday has, in the paper referred to, 

 made certain statements with respect to the opinions of Sir Humphry 

 Davy relative to the conducting powers of dry nitre, and caustic pot- 

 ash and soda, when in fusion by heat, and also with regard to other 

 matters connected with voltaic electricity, which are not correct; and 

 vindicates Sir Humphry Davy from the charge of want of perspicuity 

 in the statement of his views of these subjects. 



A Note by Mr. Faraday on the preceding Remarks by Dr. Davy 

 was then read, in which he replies to the charges there brought for- 

 ward, and justifies those statements, the accuracy of which had been 

 impugned by Dr. Davy. 



January 29. — The reading of a paper was commenced, entitled, 

 ** Experimental Researches in Electricity. Ninth Series." By Michael 

 Faraday, Esq., D.C.L., F.R.S. 



February 5. — Mr. Faraday's paper, entitled, " Experimental Re- 

 searches in Electricity. Ninth Series," was resumed and concluded. 



In the series of experiments which are detailed in this paper, the 

 author inquires into the causes of some remarkable phaenomena rela- 

 ting to the action of an electric current upon itself, under certain cir- 

 cumstances, whereby its intensity is highly exalted, and occasionally 

 increased to ten, twenty, or even fifty times that which it originally 

 possessed. For the production of this effect, the principal condition 

 is that the current traverse a considerable length of a good conductor, 

 such as a long wire j more especially if this wire be coiled in the form 

 of a helix j and the effect is still further augmented when this helix is 

 coiled round a cylinder of soft iron, constituting an electro-magnet. 

 The evidence on which these conclusions are founded is the following. 

 If an electromotor, consisting of a single pair of zinc and copper 

 .plates, have these metals connected by a short wiredipping into cups 

 of mercury, the electric spark consequent upon either forming or 

 breaking the circuit is so slight as to be scarcely perceptible; but if 

 a long wire be employed as the medium of connexion, a bright spark 

 is obtained on breaking the contact. If the wire be coiled in a helix, 

 the spark is still brighter j and if a core of soft iron be placed within 

 the helix, the spark, at the moment of disjunction, is more brilliant 

 than in any of the former cases : and the higher intensity of the cur- 



