English Mahogany Cased Dip Circle Start Price USD 150.00 Current Price USD 157.50 Time Left - Bid Count 2 Buy It Now Price - Reserve Price - Start Time Tuesday, August 26, 2008 End Time Tuesday, September 02, 2008 Location Fallbrook, CA See more about 'English Mahogany Cased Dip Circle' Description English Mahogany Cased Dip Circle Description - English, 4th quarter 19th century, unsigned. Made of mahogany and standing 9 3/4" tall overall on its 3 brass screw levelling base. The 5 1/2" wide needle case has a bubble level on top and beveled glass sides. The 3 1/4" long needle is supported on metal bearings in the center of the vertical circle, and both the horizontal and vertical silvered circles are graduated in degrees. From Turner's 19th Century Scientific Instruments: "The magnetic needle in this instrument moves in a vertical plane, in contrast to the compass, where the needle moves in a horizontal plane. Its purpose is to measure the vertical component of the Earth's magnetic field, discovered in about 1576 by the Elizabethan navigator and instrument maker, Rober Norman (fl. 1570-90), who invented the dip circle. The angle of dip was at first thought to provide the means of finding the latitude, but this proved not to be true. But the dip circle continued to be made as equipment for the scientific explorer, who needed to study the Earth's magnetic field. In this role, it was taken on scientific expeditions throughout the nineteenth century." Condition - The dip circle is in good display condition, however the top appears to be slightly canted, though it can leveled using the leveling screws and bubble level. Payment - We accept Visa and MasterCard as well as check or money order. Shipping - Buyer prepays plus shipping & insurance at cost. Sales Tax - California residents add 7.75% sales tax or send a resale card. Listing created with eLister 2.7.4 for Macintosh from Black Magik Software. Place a Bid!