The first section of the paper refers to the conditions which influence the induction of a current on itself, as in the case of a long wire and a spiral conductor. These are shown to depend on the intensity and quantity of the battery current, and on the length, thickness, and form of the conductor.

The next section examines the conditions necessary to the production of powerful secondary currents, and also the changes which take place in the same, when the form of the battery, and the size and form of the conductor are varied. The important fact is shown, that not only a current of intensity can be induced by one of quantity, but also the converse, that a current of quantity can be produced by one of intensity.

The third section relates to the effect of interposing different substances between the conductor which transmits the current from the battery, and that which is arranged to receive the induced current. All good conducting substances are found to screen the inducing action, and this screening effect is shown, by the detail of a variety of experiments, to be the result of the neutralizing action of a current, induced in the interposed body. This neutralizing current is sepa rately examined, and its direction found to be the same as that of the battery current. The question is then raised, how two currents in the same direction can counteract each other? An answer to this question is given in a subsequent part of the paper.

The fourth section relates to the discovery of induced currents of the third, fourth, and fifth orders;—that is, to the fact that the second current is found capable of inducing a third current, and this latter again another, and so on. The properties of these new currents are next examined, and the screening influence is found to take place between them; quantity is induced from intensity, and conversely; magnetism is developed in soft iron; decomposition is effected, and intense shocks are obtained, even from the current of the fourth order. A remarkable and important fact is stated in reference to the direction of these currents. If the direction of the battery current and that of the second be called plus, then the direction of the third current will be minus, of the fourth current plus, of the fifth minus, and so on. The application of the fact of these alternations is made to the explanation of the phenomenon of screening before mentioned, and also to the improvement of the magneto-electrical machine.

The last part of the paper relates to the discovery of secondary currents, and of currents of the several orders, in the discharge of

ordinary electricity. Shocks are obtained from these; the screening influence of good conductors is shown to take place; magnetism is developed; and the alternations in the direction are found to exist as in the currents from galvanic induction. Some remarkable results are given in reference to the great distance at which the induction takes place. Experiments are detailed in which needles were made magnetic, when the conductors were removed to the distance of twelve feet from each other.

Prof. Henry made a verbal communication, during the course of which he illustrated, experimentally, the phenomena developed in his paper.

Stated Meeting, November 16.

Present, twenty-four members.

Mr. DU PONCEAU, President, in the Chair.

The following donations were received:

FOR THE LIBRARY.

The Good Fellow, by Paul de Kock. Translated from the French by a Philadelphian. Two Volumes. Philadelphia, 1837.-From Daniel J. Desmond, Esq.

Allgemeiner Hand-Atlas der Ganzen Erde. Weimar, 1811.From the same.

Kongl. Vetenskaps-Academiens Handlingar, för Aor 1836. Stockholm, 1838.-From the Academy.

Aorsberättelse om Framstegen i Fysik och Kemi afgifven den 31 Mars

1836; af Jac. Berzelius. Stockholm, 1836.-From the Royal Swedish Academy.

Aorsberättelse om Technologiens Framsteg afgifven den 31 Mars

1836; af G. E. Pasch. Stockholm, 1836.-From the same. Aorsberättelse i Astronomien af S. A. Cronstrand. Den 31 Mart.

1836. Stockholm, 1836.-From the same. Aorsberättelser om Nyare Zoologiska Arbeten och Upptäckter, afgifne

den 31 Mars 1835 och 1836, af B. Fr. Fries. Stockholm, 1837. -From the same.

Aorsberättelse om Botaniska Arbeten och Upptäckter för Aor 1835. Afgifven den 31 Mars 1836. Af Joh. Em. Wikström. Stock

holm, 1837.-From the same.

Tal om Hydraulikens närvarande tillstand m. m. Af P. Lagerhjelm. Stockholm, 1837.-From the same.

Aminnelse-Tal öfver Kongl. Vetenskaps-Academiens Framlidne Ledamot Friherre Lars A. Mannerheim, af A. G. Mörner. Stockholm, 1837.-From the same.

Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin. Aus dem Jahre, 1836. Berlin, 1838.-From the Academy.

Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königl. Preuss. Akademie der Wissenschaften zu Berlin. For July, Aug. Sept. Oct. Nov. & Dec. 1837; and Jan. Feb. March, April, May, & June, 1838. Berlin, 1837-38.-From the same.

Essai sur le Madar, (Calotropis Madarii Indico-Orientalis) contenant l'Histoire naturelle de cette Plante, ses propriétés physiques, chimiques, et médicinales. Par J. N. Casanova, C. M. D. Traduit de l'Anglais par L. A. Richy. Calcutta, 1833.-From the Author.

General Observations respecting Cholera Morbus. By J. N. Casanova, C. M. D. Philadelphia, 1834. From the Author.

A Lecture on the Social and Moral Influences of the American Revolution. By Job R. Tyson. Philadelphia, 1838.-From the Author.

The American Journal of the Medical Sciences. Edited by Isaac Hays, M. D. No. XLV, for November. Philadelphia, 1838.From the Editor.

Transactions of the Agricultural and Horticultural Society of India. Vol. V. Serampore, 1838. From the Society.

Agricultural Society of India. Proceedings. Four numbers. From Jan. to April. Calcutta, 1838.-From the same.

FOR THE CABINET.

Three specimens of quicksilver ores, eight of silver ores, and fourteen of copper ores, from different localities in Chili; six specimens of various ores and minerals, also from Chili; eight fossils from the Cordillera; an ostrich egg from the Pampas of Buenos Ayres.—

From Dr. J. N. Casanova.

The Committee on the solar eclipse of the 18th of September, made a further Report in part, comprising the following observations:

No. 30. Observation of A. Holcomb, at his Observatory, Southwick, Mass., with a seven feet Herschelian of his own construction, power 225, with red screen glass. Southwick is in latitude 42° 0' 41" north; longitude 4h 51m 12s, by Mr. Holcomb's triangulation with Springfield Court House, one of the points determined by Mr. Paine. Mr. S. C. Walker finds, from Mr. Holcomb's observation of the solar eclipse of 1836, for this longitude 4h 51m 13.2s. Mean value 4h 51m 12.6s.

h m S

Beginning, 3 20 19 Mean time.

End, 5 50 27
Duration, 2 30 8

Do.

Observation satisfactory.

Doubtful one second. Sun's limb tremulous, and near horizon.

No. 31. Observation of Prof. Albert Hopkins, at the Observatory of Williamstown College, Mass. Latitude, 42° 42' 44", longitude 4h 52m 528. Astronomical clock regulated by a four feet transit instru

ment.

h m

Beginning, 3 17 19.9 Mean time.
End,

Good observation.
(not observed) Sun too near the horizon.

The Committee on Dr. Hare's paper on the Tornado which passed over a suburb of Providence, R. I., in August last, reported in favour of publication, and the Report was adopted.

The phenomena and facts, stated in this paper, are quite consistent with those mentioned upon the authority of Prof. Bache, Mr. Espy, and other observers, relative to the Tornado which took place in New Jersey, at or near New Brunswick, in June, 1835, and of which an account will be found in the last volume of the Transactions of the Society. This paper embraced a letter from Zachariah Allen, Esq., a highly respectable gentleman of Providence, who was an eye-witness of the Tornado, having been quite as near to it as was consistent with safety. One of the facts noticed by Mr. Allen, Dr. Hare considers as tending to justify his opinion, that the exciting cause of these meteors is electrical attraction. Mr. Allen alleged that, as soon as the Tornado came into contact with the surface of the river, the water rose in a foam; that, under these circumstances, two flashes of lightning passed between the water and the overhanging clouds;

and that, after each flash, there was a perceptible subsidence of the foam. This result is precisely what Dr. Hare conceives would ensue, if the foam arose from an attraction between the water and the stratum of air above, caused by opposite states of electrical excitement. In such case, the passage of sparks always necessarily tends to restore the equilibrium between the electrified masses, and consequently to lessen their reciprocal attraction.

Dr. Hare made a verbal communication in relation to his compound blowpipe. He stated that, having, in a letter to the chemical section of the British Association, mentioned the fusion of twenty-five ounces of platinum, of which he had already informed the Society, a Mr. Maugham, who is employed at the Adelaide Gallery in London to exhibit the hydro-oxygen microscope, had asserted that the fusion in question had been accomplished by a blowpipe of a kind which he had contrived, and of which one had been bought by Dr. Hare when in London.

Dr. Hare said he would not have considered this ridiculous and groundless allegation worthy of notice, had it not been made before the chemical section of the British Association, and had not the individual, by whom it was made, been honoured by a British society with a premium for the instrument which he miscalled his blowpipe. This blowpipe differed immaterially from one of which he, Dr. Hare, had published an engraving and description in Silliman's American Journal of Science for 1820, (Vol. II., page 298, fig. 3;) being a modification of his blowpipe described in Vol. XIV. of Tilloch's Philosophical Magazine for 1802.

The only difference between the instruments described and represented in those publications, and that employed by Maugham, was that the latter formed near the apex an acute angle, so as to be convenient for directing the flame upon a cylinder of lime for producing the lime-light.

With a view to show this method of illumination, agreeably to the process in which a revolving cylinder of lime is employed, Dr. Hare stated that he had purchased one of the crooked blowpipes alluded to; but he had never used it for any purpose, having found his own blowpipe abovementioned preferable, when the jet was directed obliquely upwards.