Roper's catechism for steam engineers and electricians .. (1899)
Roper, Stephen. [from old catalog], Keller, Edwin R., [from old catalog] ed, Pike, Clayton W., [from old catalog] ed · Philadelphia, D. McKay · leaf 276
by tapping the glassthey are free to moveand set themselves intolines corresponding to thelines of magnetic force as shown in the cut. Q. Why are the lines of filings more dense atsome points of the field than at others ? A. Because the strength of the magnetic forceis greater at those portions of… … 256 ropers catechism for A. Principally straight lines from the north tothe south pole. Q. How can you obtain the field due to a cur-rent in a straight wire ? A. By drilling a hole in the piece of glass andpassing the wire vertically through this hole andthen dusting on iron filings. Q. AVhat are…
Steam engineering · Electrical engineering
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer01inte-88-15.webp)
