|The Physical Object|
|Pagination||227 p. :|
|Number of Pages||227|
Elementary and practical treatise on subterraneous surveying, and the magnetic variation of the needle. London, John Weale, (OCoLC) Material Type: Document, Internet resource: Document Type: Internet Resource, Computer File: All Authors / Contributors: Thomas Fenwick. Full text of "Elementary and practical treatise on subterraneous surveying, and the magnetic variation of the needle" See other formats. Elementary and practical treatise on subterraneous surveying, and the magnetic variation of the : fl. Thomas Fenwick. Subterraneous surveying: with and withour the magnetic needle / By Thomas. Fenwick and d "A treatise on subterraneous surveying, " by Thomas Fenwick, forms the basis of the present work. cf. of access: Internet Topics: Mine surveying.
Full text of "Subterraneous surveying with and without the magnetic needle" See other formats. A Treatise on Subterraneous Surveying and the Variation of the Magnetic Needle. Fenwick, Thomas. Catalogue No. k £ ($). Sir William Gilbert (left) published the first scientific treatise on the earth's magnetic field entitled De magnete. In this work, Gilbert showed that the reason compass needles point toward the earth's north pole is because the earth itself appears to behave as a large magnet. 1. Bent Needle 2. Bent Pivot 3. Sluggish Needle 4. Plane of Sight Not Vertical 5. Electrically Charge Compass Box 6. Local Attraction 7. Magnetic Variation 8. Errors in Reading The Needle 1. Bent Needle -All observed Bearings will have a constant error, Either end of the needle will read higher or lower than the correct value.
A Theoretical and Practical Treatise on Subterraneous surveying, and the Magnetic Variation of the Needle, (Newcastle-upon-Tyne, ), pages and 7 folding plates. This was the primary work on mine surveying for which no Later editions were published in and The needle being perfectly at liberty, and coming to rest in the line n s, that line will represent the magnetic meridian; and the arc, n N, the angle of variation; that is, if the angle N C n, be 22° 30', then the needle will have 22° 30' variation; and as n is on the left-hand, or West side of N, the variation . The Book of Sanskrit Being and Elementary Treatise on. Magnetic Meridians. —With the exception of a few mines where some magnetic ore is worked, every mining plan has marked upon it the magnetic meridian, and in the vast majority of mines the underground survey is made with the magnetic needle; therefore the correct fixing of the meridian is of the very highest importance.