440 ^nt*. 



of the intensity of the longitudinally-applied magnet i>ii 

 force if the latter exceeds a certain minimum value. 



9. The author has investigated these phenomena by means of 

 cores constructed of iron wire (annealed) covered with insulatii 

 material overwound with insulated copper-wire coils, the latter being 

 wound in every case in a helix returning axially upon itself, so that 

 the current in this copper wire should have null effect in directly 

 generating any induced electromotive forces along the iron-wire core. 



10. The effects obtained are considered by the author to be akin tn 

 those obtained by Villari,* in 1865, by the mechanical agitation 

 iron bars through which electric currents had been previously ps 

 and, like the effects of Villari, to be due to the production and sul 

 sequent disappearance of a circular magnetisation. They are 

 akin to those observed by Hughesf with the induction balance. 



11. The author has been able to imitate and reproduce these effe 

 by th } use of copper wires immersed in iron filings, and surrounc 

 by a magnetising coil wound so as to return axially upon itself. 



Presents, April 9, 1891. 

 Transactions. 



Calcutta : Asiatic Society of Bengal. Journal. Vol. LV! 

 Parti. No. 3. 8vo. Calcutta 1890; Journal. Vol. L VI 

 Part 2. No. 5. Vol. LIX. Nos. 2-3. 8vo. Calcutta 1890;' 

 Proceedings. 1890. Nos. 4-10. 8vo. Calcutta 1890-1891. 



The So< 



Indian Museum. Catalogue of the Mantodea. No. 2. 8vo. 

 Calcutta 1891. The Museum.' 



Cambridge, Mass. : Harvard College. Annual Reports. 1889-90. 

 8vo. Cambridge 1891. The College. 



Museum of Comparative Zoology. Bulletin. Vol. XX. No. 8. 

 8vo. Cambridge 1891. The Museum. 



Edinburgh : Geological Society. Transactions. Vol. VI. Part 2.' 

 8vo. Edinburgh 1890. The Society. 



Royal Society. Transactions. Vol. XXXIV (The Meteoro- 

 logy of Ben Nevis). 4to. Edinburgh 1890. 



The Director, Ben Nevis Observatory. 



Essex Field Club. The Essex Naturalist. Vol. IV. Nos. 10-12. 

 8vo. Buckhurst Hill 1891. The Club. 



Heidelberg : Naturhistnrisch-Medicinischer Verein. Verhand- 

 lungen. Bd. IV. Heft 4. 8vo. Heidelberg 1891. 



The Society. 



' Poggendorff, Annalen,' vol. 126, 1865, p. 87. 

 t ' Boy. Soc. Proc.,' Yol. 31, 1881, p. 631. 



