254- Mr. G. Dakin's proposed Improvements in the Construction 



plate, balls, &c. When fixed at the end of the upper con- 

 ductor, it will bring the wooden points, &c. forward into the 

 room, and obviate the employment of the insulated handle 

 and chain. 



The discharger consists of a ball with a short rod and ring: 

 at right angles to this is a ferule to fit the glass rod : at the 

 other end of the rod is a ferule with a female screw. The 

 stand is made of brass, with a large hollow edge turned up 

 smooth. It answers three distinct purposes well, and does 

 away with the discharging rod, which is a dangerous thing to 

 use with a battery in the dark, and is of little use unless it 

 be to take the residuum out of jars set also with Lane's dis- 

 charging electrometer, which when fixed on the top of the 

 jar is extremely cumbrous and liable to be broken. I have 

 seen this latter fitted up with a micrometer screw : the ab- 

 surdity of this must be evident to any practical electrician, 

 especially if there should be the least dust in the room; in 

 fact, the eye is quite capable of judging of any distance that 

 is required to proportion the strength of the shock. The 

 third purpose it answers is that of the upper plate and handle 

 of the electrophorus : this is generally made so short, that if 

 the operator has a moist hand it is almost useless. When 

 used as a discharging rod, the hand is applied to the lower 

 ferule, and the whole is moved up to any part of the conduc- 

 tor. When used as Lane's discharging electrometer, there 

 is a slit and screw to fix it at any required distance : by this 

 means it is more secure than the latter, as the twitching of 

 the patient is apt to increase the distance of the balls without 

 the operator being aware of it, which has often produced un- 

 pleasant consequences. When used as the upper plate of 

 the electrophorus, the upper part is taken off, the stand also 

 screws into the charger, and forms the upper plate for char- 

 ging as tratum of air, the dancing figures, &c. By this ap- 

 paratus all discharges are safely and conveniently made in the 

 dark, whether of battei'ies, jars, or spiral tubes, &c. ; and there 

 will be no occasion to attach to the latter either balls or stands, 

 if they have two hooks, one to hang in the ring and the other 

 to touch the bottom. 



The show jars of the shops are generally taken to make 

 the Leyden jars of, the thick bottoms of which are reckoned 

 as coated surface, though they are known to receive only 

 weak charges. Now if this almost useless part was forced 

 upwards so as to form an inverted jar, and the middle of this 

 back again, as shown in the engraving, (how often this may 

 be repeated must be left to the glass-blower,) we should have 

 a jar that would have at least twice the power of an ordinary 



jar, 



