TO ELECTRICIANS, &c. 



To be Sold on reasonable Terms, 



AVERY Elegant ELECTRICAL MACHINE, the largest in Eng, 

 land; haA'ing a Plate of Ghu.s 51 Inches Diunieter; and mounted 

 Avith. appropriate Brass Conductors, on stout insulating PiUars. Also 

 several Cylinder Eioctrical Machines of <;teat Power, arid of very superior 

 Construction. Some Batteries, Jars, ' Electrometers, Electric Columns, 

 Air-pumps, and other Articles of Apparatus, many of them Original and 

 of known Excpilencc, being Duplicates from the extensive Collection of 

 Mr. SINGER. 



The Instruments maybe viewed, and Particulars known, by application 

 at No. 3, Princes Street, Cavendish Square. 



Just Imporiod by John and Arthur Arch, 61, Cornhill, 



ANEW and CORRECT MAP of the UNITED STATES of 

 NORTH AMERICA, on six Sheecs, exhibiting the Counties, 

 Towns, Roa-^s, &c. iu each Stale, carefully compiled from Surveys, and 

 the most authentic Documents. 



By SAMUEL LEWIS. 

 Philadelphia, published by Emmor Kimber, 1815. 

 Size of the Map, five Feet eiglit Inches high, by six Feet three Inches 

 wide. Price Ql. (is. mounted on Canvass and Rollers, and varnislied. 



ENGRAVINGS, 



Vol. XLI. Pepys's Mercurial Voltaic Conductor. — Leslie's Dif 

 ferential Thermometer. — Diagrams to illustrate Dr. Wollaston's Peri- 

 scopic Camera Obscura and Microscope. — Count Rumforp's improved 

 Coifee-pots. — Mr. Goss's Instrument to work Addition of Numbers 

 willi Accuracy and Dispatch. — Mr. Davis's hanging Scaffold; and 

 Mr. Martin's Method of relieving a Horse from a Cart when fallen 

 dovm in iis Shafts. — A Quarto Piire to illustrate Mr. J. Hicks's Ac- 

 count of the Situation and Means of raising the Ro)al George. — A Plate 

 to illus rate Mr, Southern's Essay on the Equilibrium of a Combination 

 of Be?vms,' Blocks, &c. and on the Polygon of Forces — A Plate to illustrate 

 Mr, Stekvkns's Accouifit of a Meteor seen at London and other Places in [ 

 March last. — A Plate to illustrate Mr. Machell's Annular Saw. 



Vol. XLI I, A Plate containing Professor Leslie's Atmometer, and! 

 Figures to illustrate Dr. Wollaston's Paper on the eiementary P^rticlesj 

 of certain Crystals. — A. Sketch of that Part of the Island of Java whichi 

 contains the natural Lake of Sulphuric Acid. — Interior of Volcano in thu 

 Island of Java, and Figures to illustrate Mr. Walker's Paper on the Elecj, 

 trie Fluid. — A Phte to illustrate M. Link's Memoir on the Anatomy plj 

 Iplants, and Dr. /Wollaston's Cryophorus. — A third Plate to illustrate 

 M. Link's Memoir on the Anatomy of Plants.— Mr. T. Jokes's Sectq-I 

 graph, — ft new Instrument for dividing right Lines into Ajual Parte, measwuf/ 

 ing AnglpB, and inscribing Polygons in the Circle, &c. 



