ELECTRICITY. 



471 





Descriptive 



Kkctrititv. 



Mr Forster 



employs the 

 olumn to 

 ring bells. 



PlATE 



CCXLV. 

 Fig. 9. 



Fig. 10. 



Different 

 forms of the 

 electric 

 column. 



Viff.ll, 

 11,13. 



When M. De Luc was engaged in these experiments, 

 Mr B. M. Forster succeeded in producing a constant 

 electrical chime, by making the action of the column 

 set in motion a brass ball, suspended by a ?ilk thread 

 between two small insulated bells, connected with the 

 two extremities of a column, consisting of I MO groups 

 of the same diameter as those used by De Luc. The 

 apparatus of the bells is represented in Plate CCXLV. 

 Fig. 9. where A, B are the two bells, supported on glass 

 pillars, and c the small brass ball which acts as a clapper 

 in ringing the bells. On the 14th of March 1810, Mr 

 Forster put this apparatus into a closet, and connected it 

 with the three columns A B, CD, EF, represented in Fig. 

 10. The bells immediately began to ring, and continued 

 till the 24th March, when the ringing ceased about a mi- 

 nute. This ringing continued without ceasing till the 

 4th of September, when it ceased about 10 minutes. 

 They began again to ring at intervals, stopping, per- 

 haps, half a second or more at a time. After this they 

 topped for several days, and at other times for hours, 

 and on the 18th of November Mr Forster removed them 

 from the column. 



Mr Forster made also a number of experiments with 

 the electric column. He found, that the electricity of 

 the column acted through a portion of air ; and he com- 

 municated a slight charge to a coated jar. 



Mr Singers, to whom electricity is under great obli- 

 gations, constructed an apparatus with the electric co- 

 lumn, which never ceased to ring for 14 months, ex- 

 cept during its removal from one place to another. Du- 

 ring an interval of 6 months, when it was never disturb- 

 ed, there was no interruption in the ringing. M. De 

 Luc has a pendulum, which hag vibrated between two 

 balls for more than two years, and still continues. 



In Plate CCXLV. we have shewn the different 

 ways in which the electric column is fitted up for 

 different purposes. The figures are taken from Mr 

 Singers' Elements of Electricity. Fig. 1 1 . represents a 

 column of 1000 series, lying horizontally upon the caps 

 of two delicate gold leaf electrometers. Fig. 12. repre- 

 sents the apparatus for ringing, which consists of two 

 vertical columns inclosed in a glass receiver, having a 

 bell fixed at the lower extremity of each, and having 

 suspended between them, by a very fine thread of raw 

 silk, a brass ball. Fig. 13. represents De Luc's aerial 

 electroscope, which consists of a vertical column insu- 

 lated and enclosed in a glass receiver. The column 

 consists of from one to two thousand series. A bent wire 

 having a ball a at its lower end, is connected with the 

 upper extremity of the column, so as to hang parallel to 

 the column, and at some distance from it. Opposite to 

 this ball a is a similar ball b, screwed into the lower 

 cap of the column, and into the same cap is screwed a 

 brass forky] with a fine silver wire stretched between 

 its prongs, for the purpose of preventing the little ball 

 from sticking, a* formerly described. The pendulum 



dc consists of a fine silver wire dc, suspending a gilt 

 pith ball, which would always be in contact with the 

 brass ball l> if influenced only by gravity. 



M. De Luc has recently observed, that the power of Effect of tiie 

 electric columns, (as pointed out by the oscillation of a sun's nyt 

 pendulum,) is increased by the action of the solar 'J d 16 e!e - 

 rays ; and this remark has recently been confirmed by J^" 

 Mr Hausmann. M. De Luc imagined, that this effect was 

 not produced by the heat of the sun ; for he remarked, 

 that a column composed of paper discs thoroughly dried 

 had very little power. Mr Singers, however, has found 

 that the power of the bell-ringing apparatus is increa- 

 sed by a moderate heat. It always pulsates most slow- 

 ly in winter ; and whenever a fire was made in the 

 room, the ringing became more rapid. When the tem- 

 perature of his apartment was 50, Mr Singers applied a 

 column of 1000 scries to the cap of a gold leaf electrome- 

 ter, and he found that the gold le:if struck the side- <>;' 

 the glass nine times in fiO seconds. He then place;! 

 the columns during 10 minutes before a fire, so that the 

 thermometer rose to 85. When the column was now 

 applied to the electrometer, the gold leaves struck the 

 side 3? times in 60 seconds. When it was removed 

 to another part of the room, so as to recover its origi- 

 nal temperature of 5G n , the gold leaves struck only nine 

 times in 60 seconds as before. 



As the following observations on the electric column Singer*' 

 are both new and ingenious, we shall make no apology observation 

 for presenting them in Mr Singers' own words. " There " e elcc " 

 appears every reason to believe, that the action of a well 

 constructed column will be permanent. I have several 

 that have been constructed nearly three years, and they 

 are still as active as at first. There is, however, a pre- 

 caution necessary to their constant and immediate ac- 

 tion. The two ends of a column should never be con- 

 nected by a conducting substance for any length of 

 tune ; for if, after such continued communication, it be 

 applied to an electrometer, it will scarcely affect it for 

 some time. It is therefore necessary when a column is 

 laid by, that it be placed upon two sticks of sealing- 

 wax, so as to keep its brass caps at the distance of about 

 half an inch from the table, or other conducting surface 

 on which it is laid ; and if a column, which appears to 

 have lost its action by lying by, be insulated in this 

 way for a few days, it will usually recover its full power. 



There is another cause of deterioration which is more 

 fatal ; it is the presence of too much moisture. If the 

 paper be perfectly dry, it is a non-conductor, and will not 

 therefore produce any action in the column. Hut this per- 

 fect dryness can only be obtained, by exposing the paper 

 to a heat nearly sufficient to scorch it ; and in its drycst 

 natural state I have always found the paper sufficiently a 

 conductor, even when, by exposing the jxiper discs to 

 the heat of the sun, they have been so dried as to warp 

 considerably. When the paper is sufficiently dry, the 

 action of the column continues without diminution . 



