Evidently this shaft of a mine, this enormous elongated mine, could replace a metal cannon the fabrication of which would have been as dear as difficult and to which it would. be necessary to give an unwieldy thickness to avoid all risk of an explosion. Barbicane & Co. had always entertained the idea of operating in this manner, and if the notebook of J. T. Maston mentioned a cannon it was that of 27 centimetres which had been used in the calculations as a basis. Consequently a spot was chosen at a height of a hundred feet on the southern slope of the chain. Nothing would be in the way of the projectile when it would fly out of the mouth of this tunnel bored in the massive rock of Kilimanjaro. It was with extreme precision and not without very hard work that the men could dig this gallery. But Barbicane & Co. could readily make perforations with simple machines put in action by means of compressed air which was secured by using the powerful falls of water from the mountains. In the holes bored through the headings of the shaft were placed charges of melimelonite. And nothing more was necessary than this violent explosive to shiver the rock, extremely hard as it was. The thousands of workmen, led by their ten co-operators under the general direction of Barbicane & Co., labored with a great deal of zeal and intelligence to bring the work to a speedy end. At the end of six months the shaft measured 27 metres in diameter and the lining of it 6 metres in thickness. As it was absolutely necessary that the projectile should glide through a bore perfectly smooth the interior of it was covered with a casting exactly prepared. In reality this part of the work was very similar to that of the celebrated Columbiad, of Moon City, which had sent the projectile to the moon. But such work as this is impossible to the ordinary engineers of this world at present. As soon as the boring was finished the workmen pushed on with the work at the second workshop.