The "day" caves of Jenolan, although grandly picturesque, are but slightly typical of the interior caverns. As the few bars of harmony dashed off by way of prelude to an intricate musical composition prepare the ear for the movement which is to follow, so an inspection of the external caves trains the faculty of observation for the ready appreciation of the more elaborately beautiful objects in the dark recesses of the enchanted mountain. The contrast between the two is as marked as the difference between the costly pearls of a regal diadem and the rough exterior of the shells which first concealed them. To explore the "night" caves it is necessary to be furnished with artificial light, and each excursionist is provided with a candle fitted into a holder, the handle of which is like the barrel of a carriage lamp, and immediately underneath the flame is a saucer-shaped guard with the edge turned inwards, so as to catch the drips from the sperm. By means of this arrangement the lights may be presented at almost any angle without doing injury to the caves, except in regard to the smoke, which although slight, is nevertheless in degree perilous to the wondrous purity of the formations. The principal features of the "night" caves are illuminated by the magnesium light, which is rich in chemical rays and burns with great brilliancy. There should not be allowed in the caves any colorific or other light which would cause smoke by imperfect combustion, or emit volatile substances likely to change the interior hues. If their pristine beauty--or as much of it as remains--is to be preserved, the caves ought to be illuminated by electricity, which will neither affect the temperature nor soil the most delicate of Nature's handiwork. The smoke of candles in a quiescent atmosphere like that of the caves, cannot fail, in process of time, to have a deleterious effect. Years ago, in the Wingecarribee country, there were some fairy gullies. The sides were flanked with sassafras columns, the roofs were covered with branches interlaced by creepers that excluded the sunbeams, and on the banks of the creeks which trickled through the centre were tree-ferns of marvellous beauty. Their perfect fronds were lovely--their growth prodigious; but that in which their charm chiefly lay was their unexampled delicacy of colour. When the natural shade was removed, and they were subject to wind, and rain, and dust, they became commonplace. They grew like other tree-ferns, and were ranked with ordinary things. So with the caves. Their wondrous beauty and attractiveness are found in their freedom from defilement. In their illumination there should be neither smoke nor heat, and it is a question whether within their precincts incense ought to be burned, even to King Nicotine. [Illustration: THE NETTLE CAVE.] CHAPTER VI. THE NETTLE CAVE.