ELECTRICITY. 



3J7 



Liko tho rate of intorost, the rate of discount depend* on tho 

 proportion liftwi-.-n lenders uii'i 



oauHOti which govern tho rate of discount, and which either do 

 ir. <>i uinicar in a very different way, when money in 

 lent ut interest. 



In ; 'o, the amount of money lent at interest JH 



:.t, in discounting billH. 



It is imp.^-ilile to guess its amount; it .includes publiu fund", 

 moneys lent on murtvMtfe <.r deln-ntir iriety of similar 



investment-.. Most of this amount, too, is lent for an ind 

 period, lint there is little doubt that the amount of pr<>' 

 or money lent at interest ia a hundred times a* much as that 

 fund which is supplied for tho purpose of discounting mercantile 

 hills, and which is in the hands of lnuiker.-, in the shape of 

 customers' deposits and shareholders' capital. In ordinary 

 times, tho amount held by those persons id amply sufficient for 

 purposes of trade. 



These funds, however, are liable to sudden and excessive 

 demands upon them. There are times in which the disposition 

 to borrow, for trade purposes, is greatly in excess of the average, 

 as when the fever of speculation is on, or when traders wish t 

 save themselves from risk. Under such circumstances, the 

 supply of loans falls short of tho demand of borrowers, and 

 the rate rises. Tho demand of borrowers may rise to a famine, 

 and a panic, as it is called, ensues in the money market. 



Other eireum- buncos, tho explanation of which would bo too 

 elaborate and difficult for elementary lessons such as those, 

 affect tho rate of discount. They arise from that artificial 

 system of currency which exists among us, and which tends to 

 render tbo variations in the rate more sharp and more frequent. 

 Thus, for example, for a great part of the year 1866, tho rate 

 was ten per cent. ; then it sank for a long period, more than a 

 year, to two per cent. But in August, 1870 that is, just after 

 tho beginning of the Franco-German war it again rose from 

 three and a half to six per cent. 



It is a common saying among economists, that the rate of 

 profit rises and falls with high or low prices of labour, being 

 high when labour is cheap, and low when it is dear. Cheap 

 and dear labour must not, however, be understood to mean, a.s 

 has been said before, high and low wages. A labourer may be 

 very highly paid, and be very cheaply paid ; and, on the other 

 hand, he may get very low wages, and be a dear bargain at the 

 money. The real test of dearness and cheapness is the efficiency 

 of labour. 



But we shall now see what the saying means, that tho rate 

 of profit rises and falls with low and high wages. That part of 

 profit which consists of interest is unaffected by the efficiency 

 of labour. Again, that portion which covers risk is equally 

 unaffected. But tho remaining portion, the compensation for 

 superintendence or management, is powerfully affected by the 

 comparative efficiency or inefficiency of labour. 



The manager of a great business is like a general conducting 

 tho operations of an army. The prospect of success or victory 

 in his undertaking depends on his own skill, and on the capacity 

 of his troops. He may have the highest abilities, but his 

 materials may bo worthless. He may have excellent materials, 

 and bo deficient in strategical power. So the manager or master 

 of some great business may have excellent workmen, and bo 

 deficient in the intelligence and acuteness needed for successful 

 trade or manufacture ; or, having this capacity, he may be dis- 

 abled from using it by the stupidity or caprice of his workmen. 

 But in any case, he is paid wages for the service which ho does 

 in controlling the details of his business, ju*t as tho workman 

 is paid wages for the work he does. Tho only difference between 

 the two is, that the wages of the manager or employer are dis- 

 guised under tho name of profits. 



A conflict, therefore, between workmen and employers is a 

 struggle as to who should get most wacro*. Xo attempt on the 

 part of the former will succeed in lowering tho rate of interest : 

 nor will it affect that part of profits which covers risk, but, on 

 the contrary, will tend to augment it. All that the workmen 

 can do is to diminish the amount which the employer r"' 

 for his own superintendence or management. But they cannot 

 do this unless the employer's remuneration is reduced all round. 

 AH workmen cannot get more, unless all employers get less. 

 Otherwise, the general tendency of profits being to an equality. 

 the less favoured calling would be deserted for one that is 

 more so. 



In thono countrie* whore wage* are highest profit* trc Highest. 

 The reason will now bo manifest. Deduct risk and intercut, 

 and profit* become wage*, and iharo in the rise whith wage* 

 achieve under tho circumstances. Now in those countries 

 where labour is scarce, land is plentiful ; and the opport 

 for occupying land advantageously being abundant, wages and 

 .I e.]ii:illy high. Such is ordinarily the case in our own 

 , where diligence and perseverance will easily secure to 

 settlers competence at first, and finally wealth. For the same 

 reason, in these countries, the rate of interest is high, for every- 

 body can employ capital advantageously ; and everybody i* 

 willing to borrow, while few are willing to lend. 



VOLTAIC ELECTRICITY. XIX. 



THE DISCOVKKT AND HISTORT OF SELENIUM ITS SENSITIVE- 

 NESS TO LIGHT DK. SIEMENS* SELENIUM EYE Til 

 1 'A RATION OF A SELENIUM CELL. 



PROFESSOR GRAHAM BELL, whoso beautiful magnetic telephone 

 has already been fully described in these pages, has given to 

 the world another wonderful instrument, which, if not at once 

 destined to work out practical alterations in methods of inter- 

 communication, may possibly form the nucleus of important 

 work in the future. The telephone, as we know, conveys speech 

 between distant places by means of a connecting lino Wire. The 

 photophone, as the new instrument ia called, utilises for this 

 purpose not a metallic wire, but a ray of light ! Before describ- 

 ing the construction of the instrument by which this marvellous 

 result is achieved, it will be necessary to give a brief history of 

 a substance which hitherto has been little known or heard of 

 beyond the precincts of the laboratory we allude to the non- 

 metallic element called selenium. 



In tho year 1817 this substance was discovered atGripsholm, 

 in Sweden, in the refuse of a sulphuric acid manufactory, by 

 Berzelius, but since that time it has been found widely dis- 

 tributed, but can only be obtained in small quantities from the 

 source already indicated, from iron and copper pyrites, from 

 silver furnaces, &c. It is obtained in two different forma, one 

 of which is soluble in carbon disulphide, the other being in- 

 soluble in the same medium. The first is known as red or 

 glassy selenium, conducting heat badly, and being a non-con- 

 ductor of electricity. The other variety is known as black or 

 metallic selenium, and it conducts heat, and under certain 

 conditions will form a good conductor of electricity. To this 

 last kind of selenium only wo wish to call our readers' attention. 

 Up to within recent years, selenium was looked upon merely as 

 a curiosity. Medallions stamped with the likeness of its dis- 

 coverer were commonly to be obtained, and were doubtless put 

 away by collectors as specimens of a rare mineral which was 

 curious, but had no particular use or application. In 1873, 

 Mr. Willoughby Smith made a strange discovery with reference 

 to this substance. Ho found that it had a peculiar property 

 which no one had before detected. Ita electrical resistance 

 varied with the amount of light to which it was subjected, the 

 difference of these variations being very great indeed. In other 

 words, the material when experimented with in darkness gave 

 great resistance to the passage of electricity, but when exposed 

 to light, the resistance was brought quite low. Mr. Willoughby 

 Smith utilised this curious property of selenium in connection 

 with the laying of long telegraphic cables, his position as elec- 

 trician -in- chief to the Telegraph Construction and Maintenance 

 Company giving him an opportunity of seeing its value in that 

 capacity. Dr. Siemens, Professor Adams, the Earl of Rosso, and 

 other scientific men, took up the subject, and made many other 

 curious observations concerning this comparatively new element. 

 Thus much was known respecting selenium when Professor 

 Graham Bell, in association with Mr. Snmner Tainter, three 

 I years ago produced tho photophone. 



In previous experiments the variation of resistance in sele- 

 nium, according to the amount of light submitted to it, had been 

 tested by a galvanometer, the needle of which was of course 

 more or less deflected according to the resistance afforded. 

 The inventor of tho telephone inferred that if that instrument 

 were to be substituted for the galvanometer, it would probably 

 emit sounds as the variations in resistance reached its coil- 

 covered magnet. He was led to this conclusion by the con- 



