but making half and quarter seconds beat, in Signor Fiodo's establishment, oscillating in directions approximating to the meridian, and to the prime vertical, but none were stopped, and on examination I found them not circumstanced so as to have been so.
I verified with care all the dimensions and particulars of the regulator that was stopped, and have not the smallest doubt either of the good faith upon which the facts taken from Signor Fiodo rest, or of the exactness of the conditions as observed by him, and the dimensions, &c., as taken by myself.
On passing into the Naples end of the tunnel (or grotto) at Pausillipo, I remarked several fine, keenly-drawn lines of nearly vertical fissures, in the perpendicular banks of yellow tufa at the right-hand, or S.E. side of the entrance, which appeared recent. The light, however, was not sufficient to enable me to decide. I therefore returned early the following morning, and by clear sunlight made a minute examination of those cracks (the occurrence of which no one had remarked as far as I could learn). I satisfied myself that they were very recent, that they were not due to any settlement or alteration by gravity alone, of the banks, nor due to any artificial work, or excavation.
The keenness of their external lips or edges, the absence of dust, cobwebs, or insect or vegetable life, within or across them, and their narrow and uniform breadth of opening about 0.2 inch, their general parallelism, and, above all, their direction in azimuth, with relation to the form and direction of face, of the bank, and their verticality, convinced me that they had been produced by the shock of the 16th December, and were due to the inertia of the
