and (C'"'—C'')=(T”—T—T+T)=(T"
(T" —T');

S

R'

but for small differences of C" and C' we may put

(C''''—C'2)=2C" (C”—C'),

that is to say, small variations of current will be proportional to the variation in the temperature of the strip.

In order to facilitate the process of determining the value of a diagram in webers or other units of current, it is only necessary, if the variations are not excessive, to average the ordinates, and to determine their value by equation (1), or from a table prepared for that purpose. The error committed in taking the average ordinate instead of the absolute ordinates, when the current varies between small limits, is evidently small, the variation of the ordinates above their mean value averaging the variations below the same.

The thin sensitive conductor may thus be utilized either to restrict the amount of electricity flowing through a branch circuit within certain narrow limits, or to produce a record of the amount of current passed through a circuit in any given time.

Transactions.

Presents, January 9, 1879.

Dresden-Verein für Erdkunde. XV Jahresbericht. Wissenschaftlicher Theil; Geschäftlicher Theil und Sitzungsberichte. 8vo. 1878. The Society. Haarlem :-Hollandsche Maatschappij der Wissenschaften. Natuurkundige Verhandelingen. Derde Verzameling. Deel 3. 4to. 1878. Archives Néerlandaises des Sciences Exactes et Naturelles. Tome XIII. liv. 1-5. 8vo. 1878. The Society. Musée Teyler. Archives. Vol. IV. fasc. 2-4. Vol. V. Partie 1. 8vo. 1878.

Helsingfors :-Societas pro Fauna et Flora Fennica. 8vo. 1875-77. Meddelanden. Häftet 2-4. 8vo.

The Musée. Acta. Vol. I. 1878.

The Society.

Innsbruck:-Ferdinandeum für Tirol und Vorarlberg. Zeitschrift. Dritte Folge. Heft 22. 8vo. 1878.

London :-British Pharmaceutical Conference.

The Institution. Transactions at the

Fifteenth Annual Meeting, held in Dublin, August, 1878.
Year Book of Pharmacy, 1878. 8vo.

The Conference.

St. Bartholomew's Hospital. Reports, edited by W. S. Church and Alfred Willett. Vol. XIV. 8vo. 1878.

VOL. XXVIII.

The Hospital.

Y

Transactions (continued).

Paris-Faculté des Sciences.

Thèses, par Delage, Haretu, de Montgolfier, Pellet, Velain, Legoux, Prunier, Halphen, Witz. 4to. 1877-78. Thèses, par Guillaud, Hollande, Velain, Richet, Flahault, Crié. 8vo. 1878 (No. 388, 399-411).

The Faculty.
St. Petersburg :-Académie Impériale des Sciences. Mémoires.
Tome XXV. No. 5–9; XXVI. No. 1-4. 4to. 1877-78. Bulletin.
Tome XXV. No. 1-2. 4to. 1878.
Venice :-Ateneo Veneto. Atti. Serie 2. Vol.

Vol. XIV. Puntata 1-2; Serie 3. Vol. I.
Venezia 1877-78.

The Academy.
XIII. Puntata 3;
Puntata 1-3. 8vo.

The Institution.
Atti. Serie 5.

Reale Istituto Veneto di Scienze, Lettere ed Arti.
Tomo III. Disp. 8-10. Tomo IV. Disp. 1–9. 8vo. 1876-78.

The Institution.

Adams (A. Leith), F.R.S. On the Recent and Extinct Irish Mammals. 8vo. Dublin 1878. Report on the History of Irish Fossil

Mammals. 8vo. 1878.

The Author. Hood (C.), F.R.S. A Practical Treatise on Warming Buildings by Hot Water, Steam, and Hot Air; on Ventilation, &c. Fifth edition. 8vo. London 1879.

Mills (E. J.), F.R.S.

The Author. Destructive Distillation: a Manualette of Paraffin, Coal Tar, Rosin Oil, Petroleum, and kindred Industries. 8vo. London 1877.

The Author.

Nicholson (H. A.) and R. Etheridge, jun. A Monograph of the
Silurian Fossils of the Girvan District in Ayrshire. Fasciculus 1.
8vo. Edinburgh 1878.
The Author.
Pictet (Raoul) et G. Cellérier. Méthode Générale d'Intégration
continue d'une fonction numérique quelconque. 8vo. Genève 1879.
The Author.
Wurtz (Ad.) La Théorie Atomique. 8vo. Paris 1879. The Author.

Transactions.

Presents, January 16, 1879.

Batavia:-Koninklijke Natuurkundige Vereeniging in Nederlandsch-
Indie. Natuurkundig Tijdschrift voor Nederlandsch-Indie.
Deel 35, 36, 37. 8vo. 1875-77.
The Society.
Breslau-Schlesische Gesellschaft für vaterländische Cultur.
Fünfundfünfzigster Jahres-Bericht. 8vo. 1878. Fortsetzung