8 MAWSON & SWAN, 



Holtz Electrical Machine (Fig. 74), working by induction without 

 rubbers, i6-in., 2 plates, ] ios. ; 4 plates, 10. 



FIG. 74. 



Bertch Machine with ebonite plate, ^4 ids. 



Holtz and Bertch Machine combined, a very handsome instru- 

 ment, ^5 ios. 



Both the Iloltz and Bertch Machines are worked by a multiplying wheel, and 

 produce a spark of great thickness and intensity. 



CYLINDER MACHINES. 



Cheap form, with cylinder 10 in. by 6 in., brass conductor, and teak- 

 wood framework, i is. 



Similar, with cylinder n in. by 7 in., on mahogany stand, i 155. 



Machine, best quality, with cylinder 6 in. by 4 in., i 55. 



' Do. do. . do. 7 in. by 4^- in., i ios. 



Do. do. do. 8 in. by 5 in., i 155. 



Do. do. do. 10 in. by 6 in., 3 35. 



Improved Fractional Machine for Submarine Operations : an exceed- 

 ingly simple instrument, constructed of ebonite, and capable of 

 firing 30 fuses at one time, ;i6. 



A set of Apparatus to illustrate the First Principles of Electricity. It 

 consists of two sticks of sealing wax, two rods of smooth glass, 

 one roughened glass rod, one rod of ebonite, one rod of brass, 

 a lath, flannel, and silk rubbers, box of amalgam, and an arrange- 

 ment for suspending the rods. Packed in a box, 22 j- 



13 and 15, Motley-street* Newcastle-on-Tyne. 



