Its importance in some respects may indeed be declared to be in advance of the electric telegraph, for that necessitates apparatus of delicate mechanism and a friendly, or at least non-hostile territory, over which the messages are sent. A predatory or hostile tribe may at any time sever the line of telegraphic wire, and cut all communications between neighbouring columns who are anxious to make their whereabouts and intentions known; but this cannot be done to the mirror system, where with no more apparatus than a small hand-glass telegraphy is established which no mortal agency can interrupt. No invention, no discovery can surpass in value this mode of silent yet eloquent communication, and only the interruption of the sun's beams by clouds or fogs can interfere with the transmission by signals, noiselessly, and in a manner almost imperceptible to all save the two interlocutors, who may be distant ten, twenty, thirty, or even forty miles.
At Gibraltar messages are by this process constantly sent across the Straits; and in Australia, Mauritius, Singapore, and even Canada, the invention has obtained for its discoverer the greatest reputation and kudos.
Some four years ago Lieutenant Parrott, of the Volunteer Engineer Corps of New South Wales, conducted a series of very successful operations in mirror telegraphy, using discs, about six inches in diameter, of polished metal covered with glass. At first the distance separating the two mirrors was from six to ten miles, but eventually the system was tested from the Kumagong mountain, about 2000 feet above the sea level, to the lighthouse at the entrance to Port Jackson, 400 feet above sea level, a direct distance of nearly forty miles. Now, when we consider that the only apparatus required is a small hand-mirror, and that no skill beyond the faculty of reflecting the sun's beam in the required direction, and of flashing "dots" and "signals" by means of a simple turn of the wrist, in the same way as the Morse telegraph is presented by flag-signals, are necessary, we must allow the vast importance of this discovery to the soldier and the sailor, more especially in savage or uncivilized warfare. Of course the whole method is dependent on the presence of sunshine, and, fortunately, Natal is seldom without this great boon. In South Africa the sun's beams are more constant than in almost any other clime, and they may be counted and depended upon during the major portion of the dry season. It is not unworthy of notice that a system of sun-signalling, not dissimilar to that established between Port Durnford and General Crealock's column, has been known and practised for some considerable time among the Nez Percés Indians of North America. Mr. F. C. Browne, of Sydney, Australia, however, gives a still more remarkable method of signalling, and states that successful feats have also been accomplished by moonlight for distances of from four to six miles. He considers, and doubtless he is correct, that it would be quite possible to supplement this sun-and-moon telegraphy on very dark nights by an analogous system of alternately obscuring and displaying at longer or shorter intervals a powerfully reflected light.
Lately at Portsmouth some highly successful experiments in night-signalling have been made by casting the electric and other powerful lights upon columns of steam; a method evidently suggested by the helioscope and use of reflecting mirrors.
CHAPTER XI.
Advance of 1st column—Description of route—Forts Crealock and Chelmsford—Causes of delay—Sickness of troops and its origin—Capture of cattle—Proposals for peace by Umsintwanga—His interview with Crealock—Surrender of Umguelumgwizi—Advance of 2nd division—Details of troops composing it—A fortified kraal—Fort built by Wood on the Umlatoosi—Patrol by Buller—Burning of five kraals in the Usipexi district—Amhlabatini—Depôt there described—Envoys from Cetywayo—Advance to White Umvolosi—Wood's camp—Lord Chelmsford's ultimatum to Cetywayo.
The actual advance of the 1st division may be said to have commenced on the 17th of June, when the gallant bluejackets and Marines (the Naval Brigade), one troop of Lonsdale's Horse, and one troop of Royal Engineers effected an important though short movement from Fort Pearson, the so-called base, to Fort Chelmsford; while the 57th Foot and Barton's Contingent pushed on to Fort Crealock. General Crealock, with his headquarters, arrived at Fort Crealock on the following day, and on the 19th reached Fort Chelmsford.
The road at starting from Fort Pearson led up a steep ascent and across a table-land, gradually sloping towards the west, with occasional slight undulations, until it came to the steep and almost cliff-like descent into the valley of the Amatikula. Here frequent outcrops of sandstone and quartz were noticeable to the engineers, whose professional enthusiasm was excited at seeing before them the materials for building a permanent fort in the district. Crystalline pebbles were plentiful, and the soil, which was in some places of a reddish hue, was at other points a pure white silver sand, both, however, being covered by a considerable layer of vegetable mould.