. Gazzette della ferrovia elettrica . uccessivelyover le piastre del cilindro dal primo al thetundicesimo punto. Queste dieci posizioni sono indicatadai numeri da 1 a 10 sulla parte superiore delcilindro. lunghezza 3| pollici. Posando questo sul suo lato su un tavolo, ho messo su di esso un pezzo di vetro che aveva verniciato su un lato e ha permesso di diventare per-fectly asciutto. Su questo vistavo uniformemente come possiblesome limature di ferro fini e poi ho toccato il plategently sui bordi per permettere che i filingssi dispongano. La bella curva 86 STRADA FERROVIA GAZETTE. 24 febbraio 1894. Mostrato in Fig. 13 erano i resu
1358 x 1840 px | 23 x 31,2 cm | 9,1 x 12,3 inches | 150dpi
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. Electric railway gazette . uccessivelyover the cylinder plates from the first to thetenth point. These ten positions are indicatedby the numbers from 1 to 10 at the top of thecylinder. 3| inches long. Laying this on its side on a table, I placed over It a piece of glass which had beenvarnished on one side and allowed to become per-fectly dry. Upon this I sifted as evenly as possiblesome fine iron filings and then tapped the plategently on the edges in order to permit the filingsto arrange themselves. The beautiful curves 86 STREET RAILWAY GAZETTE. Feb. 24, 1894. shown In Fig. 13 were the result. The glass wasthen carefully lifted from the magnet and heatedover a gas flame. This softened the varnish sothat the filings were stuck to the plate and whenthe varnish had hardened again were preservedfor the making of this cut. Fig. 1.3 shows thelines of force emanating from this magnet whenthe armature or keeper Is entirely removed.Fig. 14 shows the lines as they were .vhen thearmature was removed about J inch from the. FIG. 13. poles and Fig, 15 shows the lines as they appearedwhen the polar ends of the magnet alone werepresented to the under side of the glass plate. We may look upon these lices of force as somany elastic bands or strings by which the mag-net attaches itself to other pieces of iron. Whenthe iron is in actual contact with the poles of themagnet, it is bound to t^e latter by a great num-ber of these strings. When we endeavor to pullthe iron away, we have to pull against the com-bined ela3tioity of all these strings. The momentwe succeed in pulling it the slightest distancefrom the magnet, a great many of these stringssnap, or pull out of the iron and disappear in themagnet just as india-rubber strings would if theycame out of a hollow tube and were attached tothe piece of iron we were trying to pull away. Aswe remove the iron still farther, moreand more ofthese elastic strings or bands snap until the ironis removed beyond the attraction of tlie magnet
