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.