THE POPULAR EDUCATOR. 



There are in Spanish three forms of the imperfect subjunctive, 

 one ending with ra (in the first person singular), another with 

 ria, and the third with se. Each of these forms is generally to 

 be rendered in English by some one of the auxiliaries, should, 

 would, might, or could, as the sense may require. These forms 

 of the imperfect are thus used : 



The form ending with se is employed only when a conditional 

 conjunction, or an ejaculatory expression of desire, or a verb of 

 command or permission, comes before it ; as 



Le dije que tomase esos libros, 

 I told Jam that he might take those 

 books. 



Era precise que espusiese mis 

 razones, it teas necessary that I 

 hould e.rplatn my reasons. 



Sometimes the conjunction que is not expressed, but under- 

 stood ; as 



Encargo le enviasen mayor can- He ordered (that) they should send 

 tidad, him a greater quantity. 



The form ending with se can be employed after the relative 

 pronouns, and after cuanto, as much as, cuantos, as many as, 

 when they are preceded by a verb expressive of an action which 

 the other part of the sentence shows to depend on choice or 

 mere contingency ; as 



Prometio que me daria todo lo He -promised me that he would give 

 que le pidiese, me everything which I might ask of 



him. 



The form ending with ria is employed (generally to express 

 a wish or condition, or what ivould be or might be done) when no 

 conditional conjunction comes immediately before the imperfect 

 tense ; as 



I Cual de los dos preferiria vmd. ? 

 which of the two would you prefer 1 



Si ella viuiese, irian, if she 

 should come, tltey u-ould go. 



This form can likewise be used when the imperfect is preceded 

 by a verb that expresses belief, trust, or promise ; and also when 

 the conjunction si (if) is used in the sense of whether ; as 



Prometio que me daria dos 

 libros, he promised that he would 

 give me two books. 



Le pregunto si su hijo iria allii, 

 he as7;ed Jinn if (whether) his sou 

 tcould go there. 



The form of the imperfect ending with ra may in general be 

 used for either the form in se or that in ria ; and is especially 

 to be preferred to the form in ria, when interrogative pronouns 

 come before the imperfect ; as 



; Ojala me hallara con ella I Oh 

 that I could ,/ind myself with her ! 



Yo quisiera que viniesen, I 

 should like tliat they u-ould come. 



It will be seen from the foregoing rules that the form in ra 

 can generally be used instead of the forms in se and rta, for we 

 can say, si yo amara, or si yo amase, if I should love ; and we 

 can say, el amara, or el amaria, he would love. But we cannot 

 use the form in r(a and that in se, the one for the other. 



Sometimes the English auxiliaries, could, might, should, and 

 would, are expressed in Spanish by a separate verb, followed by 

 the infinitive ; as 



No queria eiitrar, he u'ould not 

 enter (was not willing to enter). 



No podia ver, he could not see 



(was not aH to see) . 



The perfect indefinite tense of the subjunctive mentions a 

 doubtful or contingent action or event as being completed, or 

 that it would have been done in past time under certain con- 

 ditions ; as 



Poco me importa que lo Laya It concerns me little whether he 

 oido decir 6 no, may have heard it spoken or, not. 



VOLTAIC ELECTRICITY. XVI. 



THE ELECTRIC TELEGRAPH. 



IT is seldom that any great discovery or invention can, with 

 fairness to others, be assigned to a single individual. Sugges- 

 tions and observations by thoughtful men often lie dormant for 

 many years, and no immediate result flows from them until 

 some master-mind gathers them up, pieces them together, and 

 presents them to the world as a startling novelty. These 

 remarks may well be applied to the electric telegraph, an in- 

 vention which has caused more changes in the conduct of the 

 world's affairs than any other contrivance conceived by the 

 mind of men. Its history presents us with a succession of step- 

 ping-stones upon which inventors trod, until the present perfect 

 results were achieved. 



But long before electricity became a power in the world, the 

 necessity of some means of conveying intelligence was recog- 

 nised, and various modes were contrived for furthering that end. 

 The signal-fires blazing out the one idea of approaching danger 

 were soon replaced by the more efficient watch-towers placed 

 at intervals for conveying signals, by means of semaphores, 

 quickly across country. These semaphores consisted of an 

 arrangement of shutters, by which several distinct signals could 

 be forwarded, and they were in use in this country up to the 

 year 1837. Long before this year had dawned, many experi- 

 menters in different countries had turned their attention to tho 

 mysteries of electricity. In Geneva, Lesage had invented a 

 system of signalling by causing two pith balls to diverge by 

 the action of a current sent through a wire at the end of which 

 those balls were hung. Lomond, in Paris, carried out the same 

 idea a few years later. The system was again brought forward 

 in this country, in the year 1816, by Mr. Ronalds, who urged 

 Government to take the matter up. But the Government of 

 the day refused to have anything to do with it, asserting that 

 the semaphore system was quite sufficient for every requirement. 

 In the meantime other inventors had contrived systems in which 

 the current was made to decompose chemical substances, as in 

 the electro- chemical telegraph of Bain. But the most notable 

 suggestion came from Ampere, of Paris, in 1821, who pointed 

 out that a galvanometer needle, by its deflections to the right 

 or the left, according to the direction of the current, could be 

 made to give signals of a reliable character. Eventually, Cooke 

 and Wheatstone, in the year 1837, carried this idea into prac- 

 tical use, and the first needle telegraph was produced. 



In all the first forms of telegraph at least two line- wires were 

 necessary, one to carry the electric current to the distant 

 station, and the other to carry back again, so as to complete 

 the circuit. But a most valuable discovery was made by 

 Steinheil, of Munich, in 1837, who showed that a return wire 

 was not necessary, and that the earth might be used in its stead. 

 From that time, therefore, it became customary only to use onu 

 wire, the necessary connection with the earth being established 

 by burying metallic plates in the ground. 



Modern telegraphic instruments may conveniently be grouped 

 into two classes. Firstly, those which transmit signals repre- 

 senting the letters of the alphabet by conventional signs, such 

 as movements of a needle, or dots and dashes on paper ; and, 

 secondly, those which transmit signals and record them in 

 ordinary printed type. In the first place we have simple appa- 

 ratus, but tho necessity for the employment of skilled operators 

 to translate the signals into readable language ; and in the 

 second case we have complex mechanism, but the advantage of 

 results which are decipherable by any one who has learnt to 

 read. The latter plan has the further advantage of less risk of 

 error than if the communication has to go through the process 

 ol: translation before being available for use. The first method 

 is adapted for the general work of the country, where a skilled 

 staff is organised to work it ; but the second has, up to recent 

 times, been mainly used for private lines. We say, up to recent 

 times, because the rapid introduction of the telephone has 

 almost superseded the use of the telegraph for private uses, 

 such as communication between offices and factories, and the 

 like. 



As representatives of the first class of instruments, we may 

 select two well-known types : (1) the single needle telegraph 

 and (2) the Morse key. Any student can easily contrive one 

 of the first-named instruments with very little trouble, and at 

 very small outlay ; and a description of the means by which he 

 may attain this end will be the best way to point out the phe- 

 nomena upon which the working of this form of telegraph 

 depends. A little toy compass, such as can be purchased for 

 a shilling, must be wound round with several turns of silk- 

 covered copper wire. It thus forms a galvanometer, the mag- 

 netised needle of which will place itself at right angles to the 

 coil of wire across it, whenever an electric current is sent 

 through that coil. The battery may consist of an ordinary 

 Leclanche cell, such as is commonly used for ringing bells. 

 When the current is cut off, the needle will instantly resume its 

 normal position (i.<?., north and south). By reversing the 

 direction of the current, by changing over the wires which touch 

 the two poles of the battery, the needle is deflected in the oppo- 

 site direction. By placing two little stops, one on either side 

 of the needle, to confine its movements within narrow limits, 



