lar notice occurs, the same rule is by universal consent followed: indeed, if uniform time were not thus kept, it would be an extremely difficult task to regulate safely the great number of trains which daily travel with varying speed over many of our principal lines, some of which must wait at definite points, while others, which run quicker, pass. With uniform time, indeed, the safe working of our crowded lines is a problem sufficiently difficult, and we can hardly conceive how much these difficulties would be increased were we to revert to the system of our forefathers, in which each place kept its own local time. Bradshaw is already confusion to many, but Bradshaw with local time would be inexplicable to all.

But the reader may ask, what is "Greenwich time?" and what "local time?" and why does Greenwich time possess such peculiar value over that of any other place as to cause it to be, so to say, at a premium? And what is "mean time?" These matters we will endeavor simply to explain. The sun, as everybody knows, determines what we call day and night, on account of the alternate light and darkness; the daily return of the sun is therefore used as our ordinary measure of time. Two kinds of solar time are of necessity employed-true solar time and mean solar time. But why two kinds of solar time? Because true solar time cannot be conveniently used in practice, as we will explain. We must premise that true solar time at any place is such as is furnished by a sun-dial; or more acurately, at noon, by noting when the shadow of a perpendicular line or rod falls due south (the true north and south line being supposed to be known), that instant being noontrue solar time. Now, let a clock at any place be set with the sun on, say April 15. Suppose the clock to go uniformly and accurately for a year, then about the same day of the year following, the clock and sun will again be together. But will they have been together throughout the intervening year? Only on three occasions-about June 14, August 31, and December 24. At all other times, the sun will have been either somewhat before or somewhat behind the clock, the greatest deviations being fourteen and a Lalf minutes in February, and a little more

than sixteen minutes in November; the sun being after the clock at the former time, and before it at the latter time. The difference is caused by inequality in the motion of the sun.* That old Sol is unsteady in his course may be new to some persons; but so it is; and as it would be extremely inconvenient to make our clocks keep with the sun throughout the year, and as the inequalities are comparatively small, we, in practice, neglect them altogether; and thus comes mean solar time, or mean time, that used in the daily business of life, as distinguished from true solar time, which agrees with mean or clock time only on four days of the year, at the times previously mentioned. The difference between the two for each day is generally given in all almanacs of repute, in a column usually headed "Clock before the Sun, or "Clock after the Sun" as the case may be. Ingenious men have in ages past constructed clocks, styled " equation clocks," to keep time with the sun; but they can be considered as little more than curiosities, and not likely ever to come into general use, could they be made ever so perfect.

We have now to consider the distinction between Greenwich time and local time. The sun, as any one can see, travels through the sky from east to west. Evidently, therefore, to all places situated on a supposed north and south line, it will be noon, or one o'clock, or two o'clock, &c., at the same instant. Thus, when it is noon at Greenwich, it is also noon at all places directly north or directly south of Greenwich; and similarly for other hours; or, in other words, the local time at all such places will be the same as Greenwich time. And manifestly, as the sun comes from the east, it will be noon at all places east of our imaginary north and south line, before it is noon at Greenwich; correspondingly, at all places to the west of the same line it will be noon

*Strictly speaking, we should say motion of the earth, but it is convenient to speak of it as motion of the sun just in the same way as when traveling on a railway, we say (erroneously), how quickly this or that object flies past, when it is ourself that is in motion. We may take the advantage of a note further to explain that the inequality spoken of due to two causes: one is the varying motion of the earth in its orbit round the sun; the other, the inclinaton of the axis on which the earth turns to the same orbit.

after it is noon at Greenwich; that is to say, local time precedes Greenwich time for all places to the east, and follows Greenwich time for all places to the west. The greater the distance of the place from Greenwich east or west, the greater will be the interval by which the local time will precede or follow that of Greenwich. Places due north or south of each other have the same local time; thus, Liverpool local time is the same as Newport (Mon.) local time, both following Greenwich by twelve minutes. The distinction between local time and Greenwich time enables us to explain also the term longitude. The difference of longitude between any two places is merely the difference of their local times, and the longitude of any place is thus its difference in time from some point fixed on as standard. The selection of a place of reference is altogether arbitrary, and in each capital city is usually adopted. The English count from Greenwich, the French use Paris, and similarly in other countries. Thus we see that Greenwich having long been the point from which longitudes were counted by the English, Greenwich time naturally came to be that universally adopted when the necessity for uniform time arose.

Before the introduction of railways, every town and village in the kingdom kept its own local time. Any person traveling in those days eastward or westward through the country, and carying a good watch, would find it gradually vary more and more from the time shown by the clocks in the districts through which he passed; and this geographical difference, combined with the real errors of the clocks, which were often extravagant, caused a state of things such as we could not tolerate now. On the establishment of railways, any attempt to work them by local time could only lead to useless complication, for in running from London to Bristol there would be a difference of ten minutes. Greenwich time was therefore employed, and gradually towns in the vicinity of railways also adopted Greenwich time, although at some places the "inovation" was opposed for a considerable period. At last, however, the use of Greenwich time came to be universal. In Ireland, Dublin time is employed. This makes a discordance between English and Irish time (English

being earlier than Irish by twenty-five minutes). Travelers coming from Ireland should bear this in mind: in going to Ireland the difference is of less consequence, as the only inconvenience would be, that in carying English time we should be always too soon. In the same way in crossing the Channel, French time (that is, Paris time) is nine minutes later than English time. The boundary of a country, and especially of an island, forms a convenient margin at which to take a new standard, as uniform time could not be used with advantage over a very large tract of country, at least not if a country extended a considerable distance eastward and westward, because in distant parts the relation between' hour by the clock and hour by the day would be partially destroyed. A small inequality does really exist in England on account of using Greenwich time, but it is trifling, and no practical inconvenience ensues.

Having explained the distinction between true solar time and mean solar time or mean time, at any one place, and also the distinction between Greenwich mean time or Greenwich time and local time, we will now consider how, principally, the clocks on railways are kept right. Let us mention here that Greenwich mean solar time, Greenwich mean time, Greenwich time, and (in England) railway time, are synonymous terms. Now, time is most acurately and regularly obtained in fixed astronomical observatories. The standard points of reference to an astronomer are the fixed stars, as the positions of the principal stars are well known. The time of being due south, or, as it is called, the "time of southing," of any one of them, being observed by the "transit instrument" the difference between the observed time and the time given in the Nautical Almanac is the error of the astronomer's clock. The clock used for such observations is a sidereal clock, one that keeps time with the stars, the length of the star or sidereal day being different from (and shorter than) that of the solar day. The er

* On account of the advance daily made by the earth in its orbit round the sun, and the great dis

tance of the nearest of the stars as compared with the distance of the sun, it takes a longer time for any point on the earth's surface to turn (by the motion of the earth on its axis) from the sun again to the sun, than it does to turn from any given star again to the same star.

ror of the sidereal clock being thus found, it is mere matter of calculation (by the same indispensable aid, the ever necessary Nautical Almanac) to ascertain the error of the mean time clock. The astronomer being compelled to obtain correct time at every opportunity, for his own use, in order to be able to record with acuracy the instant at which any phenomenon that he may observe takes place, nothing is more natural than that he should willingly dispense to the public, for their benefit, that which he must, so to say, keep on hand. By connecting any such observatory to the electric telegraph system, this can be done to any extent. The observatories which have given greatest facilities in this way are, so far as we know, those of Greenwich and Liverpool in England, and Edinburgh and Glasgow in Scotland.

The distribution of time from Greenwich is very extensive. There is in the observatory at that place a clock which is kept showing exact Greenwich time, and this clock once each hour automatically indicates the time by telegraph to various points in London. One place at which time is thus received is the principal of fice of the Electric and International Telegraph Company; and in their office is a time-distributing aparatus, or "chronopher," the function of which is to distribute in many directions the signals received from Greenwich. A grand distribution is made at 10 A. M. every day. The instrument so alters the connections of a great number of provincial wires used in the ordinary telegraphic work, that the Greenwich signal at that hour causes signals instantaneously to pass out on all these wires, indicating the time simultaneously at places north, south, east and west, to the extreme ends of the kingdom. All this is done certainly and promptly, entirely by automatic means. In this way, clocks on railways and in distant parts of the country become regulated, the town and village clocks being in their turn rectified by the neighboring railway clocks.

The part played by the observatories of Liverpool, Edinburgh, and Glasgow in the work of time-distribution, differs from that in operation at Greenwich, the signals furnished by the observatories at those places being used principally for

the control of clocks in the neighboring districts. Greenwich time is of course used. We may just say that, suppose at Edinburgh, Edinburgh time has been found by astronomical observation, the known difference between Edinburg and Greenwich time is then allowed for, and the Greenwich time so found is that given to the public. Now, before making special reference to what is doing in the way of controlling clocks in the places mentioned, we will speak further of the plan itself, as it is one likely to be of very considerable use, and well deserves to be generally known. Some years ago, when galvanism first began to be of practical use to mankind, ingenious mechanicians invented systems for working clocks by use of this power alone, doing away with the customary weight or spring. We may instance the clocks of Bain and Wheatstone as among the earliest contrivances of this kind. Such clocks required only a simple train of wheels; they did not want winding up, and would go as long as the galvanic battery endured. It began to be supposed that a great advance had been made. In course of time, however, it was by universal consent allowed, that to depend entirely upon galvanic power was an unnecessary refinement at the best, if not indeed a mistake; the disadvantages (which need not be entered into here) outweighed the advantages, and galvanic clocks came into bad repute. The most valuable horological use of the power had not then been discovered that of using it as an auxiliary only. But plans for its employment in this way began to be proposed, the most notably successful being one patented by a Mr. R. L. Jones about ten years ago. It consists as follows: Taking an ordinary wind-up clock, with seconds pendulum, the bob of the pendulum is removed, and a galvanic coil substituted. The coil is similar to a bobbin or reel of cotton, supposing the cotton to represent copper-wire, insulated, so that the successive turns of the wire shall not touch each other: the coil is fixed with the hollow horizontal. Now, if we set the clock going, it will still accumulate error as before. But let it be placed in telegraphic connection with some distant clock from which a galvanic current is received at each second

minster clock is not controled by any other, and has thus to depend on its own merits. Telegraphic communication with Greenwich exists for the purpose of enabling the clock to report automatically its state every day to the Astronomer-royal; the Greenwich record, therefore, demonstrates the goodness of the machine. It is not allowed to deviate more than two seconds from true time, and we are told in one of the Astronomer-royal's Reports, that "the rate

ledge. The electrician, on the other hand, cannot vie with the astronomer in his vocation, but possesses facilities for disseminating that knowledge to the world; and by mutual good-will mainly do the systems which we have described exist. May such combinations ever continue to flourish and extend!

Macmillan's Magazine.

to much less than one second per week." When we consider what is the duration of a second of time, and that such a large machine* is able to perform for a week within that limit, we may well marvel at the result, proving as it does the advance made in horological art. The people of London admit the goodness of the standard; and at the clubs, &c. Westminster time is now, by universal consent, adopted as the representative of Greenwich. But this is not sufficient for all London; and it is to be regretted that what has been done in some of our northern cities does not incite the citizens of London to follow so good an example, one, indeed, which might be also imitated with advantage in many of our large towns.

To railways, and their attendant telegraphs, is the improvement so far made in the system of time-keeping in the kingdom due. Wheresover they penetrate, correct time should be easily attainable; and in our days, when we live so fast, and can scarcely stem the current of our daily work, an exact knowledge and an economical use of so important an element is not to be disputed. We trust, therefore, that our endeavor to show, in a familiar way, what has so far been accomplished, will be acceptable to our readers, if only as illustrating the benefit arising from cooperation. The astronomer, possessing a knowledge of that which is so useful to mankind, has not the means of promulgating that know

*The clock-frame, carrying the various trains of weels, &c. is 15 feet long, and 4 feet 7 inches wide; the pendulum, which makes one vibration in two seconds, weighs between 6 and 7 hundredweight; the dials, of which there are four, and which are illuminated at night, are each 22 feet in diameter; and it is a day's work for a man to wind the clock up, both going and striking parts.

IN SHAKESPEARE'S PLAY OF

MACBETH.

BY FANNY KEMBLE.

MACBETH is pre-eminently the Drama of Conscience. It is the most wonderful history of temptation, in its various agency upon the human soul, that is to be found in the universal range of imaginative literature. Viewed in this aspect, the solemn march of the tragedy becomes awful, and its development a personal appeal, of the profoundest nature, to every one who considers it with that serious attention that its excellence as a work of art alone entitles it to command. To every human soul it tells the story of its own experience, rendered indeed more impressive by the sublime poetry in which it is uttered; but it is the truth itself, and not the form in which it is presented, which makes the force of its appeal; and the terrible truth with which the insidious approach of temptation— its imperceptible advances, its gradual progress, its clinging pertinacity, its recurring importunity, its prevailing fascination, its bewildering sophistry, its pitiless tenacity, its imperious tyranny, and its final hideous triumph over the moral sense--is delineated, that makes Macbeth the grandest of all poetical lessons, the most powerful of all purely fictitious moralities, the most solemn of all lay sermons drawn from the text of human nature.

In a small pamphlet, written many years ago by Mr. John Kemble, upon the subject of the character of Macbeth, and which now survives as a mere curiosity of literature, he defends with considerable warmth the hero of the play from a charge of cowardice, brought against him either by Malone or Steevens