[A] Mr. Speed, superintendent of the gardens at Chatsworth, has recently prepared his own spawn, as described on p. 73, and with perfect success. I was informed that coal-mines are not adapted for growing mushrooms, and the smallest particle of iron in the beds of manure is avoided by the spawn, a circle around it remaining inert. It is said to be the same with coal. If an evil-disposed workman wishes to injure his employer, he has only to slip along by the beds with a pocketful of rusty old nails, and insert one here and there. [Illustration: Fig. 25. View in old subterranean quarries devoted to mushroom culture, and in the occupation of M. Renaudot. Sept. 29, 1868.] The beds remain in good bearing generally about two months, but sometimes last twice and three times as long. A useful contrivance for facilitating the watering of the beds has lately been invented; it consists of a portable water-cistern to be strapped to the back and fitted with a rose and tubing, so that a workman may carry a larger quantity of water, and apply it more regularly and gently than with the old-fashioned watering-pots--while one hand is left free to carry the lamp. An iron frame has also been invented, in which the bed is first compressed and shaped, the frame being then reversed and the bed placed in position. Another invention for earthing the beds over as soon as the spawn has taken will soon be in operation if not already so. As on an average 2500 yards of beds are made every month, simple mechanical contrivances to facilitate the operation will prove of the greatest advantage to the cultivator. In addition to the caves in the localities above alluded to there are other places near Paris where the culture is carried on--notably at Moulin de la Roche, Sous Bicêtre, near St. Germaine, and also at Bagneux. The equability of temperature in the caves renders the culture of the mushroom possible at all seasons; but the best crops are gathered in winter, and consequently that is the best time to see them. I, however, saw abundant crops in the hottest part of the very hot season of 1868. These mushroom caves are under Government supervision, and are regularly inspected like any other mines in which work is going on. As regards the depth at which this culture is practised, it usually varies from twenty to one hundred feet, sometimes reaching one hundred and fifty and one hundred and sixty feet from the surface of the earth. They are so large that sometimes people are lost in them. In one instance the proprietor of a large cave went astray, and it was three days before he was discovered, although soldiers and volunteers in abundance were sent down. Is it possible that in a great mining and excavating country like ours we cannot establish the same kind of industry? CHAPTER VII. CULTURE ON PREPARED BEDS IN THE OPEN AIR IN GARDENS AND FIELDS.