He observed that the wax candles which were used in his palace and in the churches burned very regularly, and with greater or less rapidity according to their size. He ordered some experiments to be made, and finally, by means of them, he determined on the size of a candle which should burn three inches in an hour. It is said that the weight of wax which he used for each candle was twelve pennyweights, that is, but little more than half an ounce, which would make, one would suppose, a taper rather than a candle. There is, however, great doubt about the value of the various denominations of weight and measure, and also of money used in those days. However this may be, the candles were each a foot long, and of such size that each would burn four hours. They were divided into inches, and marked, so that each inch corresponded with a third of an hour, or twenty minutes. A large quantity of these candles were prepared, and a person in one of the chapels was appointed to keep a succession of them burning, and to ring the bells, or give the other signals, whatever they might be, by which the household was regulated, at the successive periods of time denoted by their burning.
As each of these candles was one foot long, and burned three inches in an hour, it follows that it would last four hours; when this time was expired, the attendant who had the apparatus in charge lighted another. There were, of course, six required for the whole twenty-four hours. The system worked very well, though there was one difficulty that occasioned some trouble in the outset, which, however, was not much to be regretted after all, since the remedying of it awakened the royal ingenuity anew, and led, in the end, to adding to Alfred’s other glories the honor of being the inventor of lanterns!
The difficulty was, that the wind, which came in very freely in those days, even in royal residences, through the open windows, blew the flames of these horological candles about, so as to interfere quite seriously with the regularity of their burning. There was no glass for windows in those days, or, at least, very little. It had been introduced, it is said, in one instance, and that was in a monastery in the north of England. The abbot, whose name was Benedict, brought over some workmen from the Continent, where the art of making glass windows had been invented, and caused them to glaze some windows in his monastery. It was many years after this before glass came into general use even in churches, and palaces, and other costly buildings of that kind. In the mean time, windows were mere openings in stone walls, which could be closed only by shutters; and inasmuch as when closed they excluded the light as well as the air, they could ordinarily be shut only on one side of the apartment at a time—the side most exposed to the winds and storms.