III. APPARATUS FOU ACCUMULATION. 275 



III. APPARATUS FOR ACCUMULATING 

 ELECTRICITY. 



1367. Leyden Jar of five and a half square feet coated 

 surface. Teyler Foundation, Haarlem. 



This jar is one of the 100 jars arranged in four cases, by which Van Marum 

 constructed a battery of 550 square feet coated surface. The coatings of 

 tinfoil have been renewed recently ; but all is restored in the form in which 

 it was used by Van Marum. 



See Van Marum, " Machine filectrique," II., p. 195. 



1368. Leyden Battery of 15 jars. 



Teyler Foundation, Haarlem. 



This battery is one of 1 6 used by Van Marum for his famous experiments, 

 giving a total coated surface of 225 square feet. 



The coatings of tinfoil have been renewed recently ; the bottom of tea- 

 k-ad in the case is also restored ; and the outer coating of the case bottom, 

 which Van Marum also made of tea-lead, has been replaced by zinc. 



See Van Marum " Machine Electrique," I. p. 155, and II. p. 3. 



1369. A Battery of 10 one-gallon Leyden Jars. 



Frederick Guthrie, F.R.S. 



This battery stands in a mahogany frame. The jars stand upon perforated 

 zinc. There is an arrangement for drying them by a current of hot air. 

 The spark from this battery deflagrates a platinum wire a foot long. 



13 69 a. A series of Leyden Jars, with connectors, hard 

 cement. Cover 10 pieces from 90 to 100mm. high. 



Warmbrunn, Quilitz, fy Co., Berlin. 



1369b. Battery of Leyden Jars, consisting of six jars 3 12mm. 

 high, in mahogany case. Warmbrunn, Quilitz, fy Co., Berlin. 



1369c. A Cylinder, on insulating support. 



Warmbrunn, Quilitz, fy Co., Berlin. 



1369d. A Cylinder, with elder-pith balls. 



Warmbrunn, Quilitz, fy Co., Berlin. 



1369e. Sphere, on insulating support, with two movable hemi- 

 spheres on shellac rods. Warmbrunn, Quilitz, fy Co., Berlin . 



1369f. Large dissected Leyden Jar. 



Warmbrunn, Quilitz, fy Co., Berlin. 



1370. Spiral Leyden Jar, Frederick Guthrie, F.R.S. 



Two sheets of ebonite, alternating with two sheets of tinfoil, are rolled up 

 together. The central knob is connected with the inner edge of the arc of 

 the foils ; the brass girdle is connected with the other sheet. A Leyden jar is 

 thus formed which is compact with a large surface. 



1371. Mica-plates for isolating electrical apparatus. 



Max. Raphael, Breslau. 



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