Transformers. 



455 



Transactions {continued) . 



Toulouse : — Faculte des Sciences. Annales. Tome VI. Fasc. 1. 



4to. Paris 1892. The Faculty. 



Turin : — R. Accademia delle Scienze. Atti. Vol. XXVII. Disp. 



1-2. 8vo. Torino. The Academy. 



Vienna: — Kaiserliche Akadernie der Wissenschaften. Anzeiger. 



Jahrg. 1892. Nr. 10. 8vo. Wien. The Academy. 



Wiirzburg ■ — Physikalisch-Medicinische Gesellschaffc. Sitzungs- 



Berichte. Jahrg. 1891. Nos. 6-9. 8vo ; Verhandlungen. 



Bd. XXV. Nr. 7. 8vo. Wiirzburg 1891. The Society. 



Zurich : — Naturforschende Gesellschaft. Neujahrsblatt. Nr. 91- 



94. 4to. Zurich 1889-92 ; Vierteljahrsschrift. Jahrg. 



XXXII. Heft 2-3. XXXVI. Heft 2-4. 8vo. Zurich 



1887-91. The Society. 



May 12, 1892. 



Mr. JOHN EVANS, D.C.L., LL.D., Treasurer and Vice-President,. 



in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The following Papers were read : — 



I. " Transformers." By John Perry, F.B.S., Professor of 

 Mechanical Engineering and Applied Mathematics, City 

 and Guilds Technical College, Finsbury. Received March 

 23, 1892. 



I. In a transformer with many circuits, of resistances in ohms and 

 numbers of turns T& u N x , R 2 , N 2 , &c. ; let the currents at any instant be 

 Ci, C 2 , &c, amperes, and let the independent electromotive forces 

 e 1? e 2 , &c, volts be maintained in them ; let I be the total magnetic 

 induction which threads through all the circuits (10 8 C.G.S. units 

 being taken as the unit of induction). The equations to the circuits 

 are : — 



e^EA+M e 2 = R 2 C 2 + N 2 0l, &c, 

 using for djdt. 



Multiplying each equation by its N and dividing by its R and 



adding, we find, using A for the ampere turns N 1 Ci + N 2 C 3 + &c. 



Nx 2 N 2 2 

 and q £or-g-+ ^-+&c, 



A + ^I = 2(Ni/R0ei (1). 



