The work began at the base, where the rock is as hard as granite. To have continued it with pickaxes would have entailed long and arduous labor, inasmuch as the wall at this place is not less than from twenty to thirty yards in thickness, but thanks to Roch's fulgurator the passage will be completed easily and rapidly.

I may well be astonished at what I have seen. The pickaxes hardly made any impression on the rock, but its disaggregation was effected with really remarkable facility by means of the fulgurator.

A few grains of this explosive shattered the rocky mass and reduced it to almost impalpable powder that one's breath could disperse as easily as vapor. The explosion produced an excavation measuring fully a cubic yard. It was accompanied by a sharp detonation that may be compared to the report of a cannon.

The first charge used, although a very small one, a mere pinch, blew the men in every direction, and two of them were seriously injured. Engineer Serko himself was projected several yards, and sustained some rather severe contusions.

Here is how this substance, whose bursting force surpasses anything hitherto conceived, is employed.

A small hole about an inch and a half in length is pierced obliquely in the rock. A few grains of the explosive are then inserted, but no wad is used.

Then Thomas Roch steps forward. In his hand is a little glass phial containing a bluish, oily liquid that congeals almost as soon as it comes in contact with the air. He pours one drop on the entrance of the hole, and draws back, but not with undue haste. It takes a certain time--about thirty-five seconds, I reckon--before the combination of the fulgurator and deflagrator is effected. But when the explosion does take place its power of disaggregation is such--I repeat--that it may be regarded as unlimited. It is at any rate a thousand times superior to that of any known explosive.

Under these circumstances it will probably not take more than a week to complete the tunnel.

_September 19_.--For some time past I have observed that the tide rises and falls twice every twenty-four hours, and that the ebb and flow produce a rather swift current through the submarine tunnel. It is pretty certain therefore that a floating object thrown into the lagoon when the top of the orifice is uncovered would be carried out by the receding tide. It is just possible that during the lowest equinoctial tides the top of the orifice is uncovered. This I shall be able to ascertain, as this is precisely the time they occur. To-day, September 19, I could almost distinguish the summit of the hole under the water. The day after to-morrow, if ever, it will be uncovered.

Very well then, if I cannot myself attempt to get through, may be a bottle thrown into the lagoon might be carried out during the last few minutes of the ebb. And might not this bottle by chance--an ultra-providential chance, I must avow--be picked up by a ship passing near Back Cup? Perhaps even it might be borne away by a friendly current and cast upon one of the Bermudan beaches. What if that bottle contained a letter?

I cannot get this thought out of my mind, and it works me up into a great state of excitement. Then objections crop up--this one among others: the bottle might be swept against the rocks and smashed ere ever it could get out of the tunnel. Very true, but what if, instead of a bottle a diminutive, tightly closed keg were used? It would not run any danger of being smashed and would besides stand a much better chance of reaching the open sea.

_September 20_.--This evening, I, unperceived, entered one of the store houses containing the booty pillaged from various ships and procured a keg very suitable for my experiment.

I hid the keg under my coat, and returned to the Beehive and my cell. Then without losing an instant I set to work. Paper, pen, ink, nothing was wanting, as will be supposed from the fact that for three months I have been making notes and dotting down my impressions daily.

I indite the following message:

"On June 15 last Thomas Roch and his keeper Gaydon, or rather Simon Hart, the French engineer who occupied Pavilion No.