Symud i'r prif gynnwys
Cuddio Rhestr Erthyglau

29 erthygl ar y dudalen hon

THE MARKETS.

[No title]

Advertising

SECOND DAY.

[No title]

[No title]

-.--BOARD OF GUARDIANS, ABERYSTWYTH.

—+ PETTY SESSIONS, ABERYSTWYTH.

INQUEST.

POPULAR READINGS.

4 COUNTY GAOL.—PUBLIC MEETING.

* THE COUNTY GAOL.

--- --------THE COUNTY GAOL.

♦ CHANCERY PENNY READINGS.

MANCHESTER AND MILFORD RAILWAY.

I ROYAL NATIONAL LIFE-BOAT…

[No title]

THE QPEEN.

----------------------I SUBSCRIPTIONS…

THE ROYALTY OF EVIDENCE; OB,…

. BLASTING BY ELECTRICITY.

Newyddion
Dyfynnu
Rhannu

BLASTING BY ELECTRICITY. On Thursday week an unusually large blast of six and a half tons (13,000 lbs.) of gunpowder was fired at the Llanymynech quarries, the property of Mr Thomas Savin, the object of the explosion being to tnrow d'iwn an enormous tuaSS of limestone rock, the estimated weight of the portion to be removed being not less than 40,000'to 50,000 tons. The charge was divided into three portions, the whole being simultaneously and most successfully ignited, by means of electricity, by Mr E. Gledhill, of the Penpompren Mines, Talybont, to whom the electrical arrangements for firing the blast were entrusted. A short discussion of the method adopted for springing a mine uf this description may not he un- interesting to some of our readers. Suppose a pre- cipice rising vertically to a height of 120 feet from the level ground, a little above the base of which rock a drift «as extended into it to a distance of 30 feet, terminating in a second drift or gallery, driven at right angles to the first, and carried in such direction from it, the total length of this driving being about 72 feet. Beneath the floor of the second gallery three small shafts were sunk at interval:; of 24 feet To the base of the rock, and at the bottom of these shafts, chambers were excavated sufficiently larg3 to hold the (jiumtity of gunpowder to be used. In this instance the chambers contained respec- tively 3 tons, 2 tons, and 1| tons of powder, making 2 6.1 1 tons in all, the charges being so regulated as to act as far as possible in accordance with the resis- tance offered by the stronger or weaker portions of the muns to be overthrown. The powder having been deposited in the cham- bers, the wires for conducting the electrical current were carefully connected with each of the charges, and carried through the drifts to the open air, and thence extended to a sufficient distance to ensure the safety of the operator. The powder was "tamped" with earth and clay, rammed tightly into the shafts and drifts, the latter being very compactly filled with the "tamping" material, to guard against the risk of a "blow out." All the necessary prepara- tions having been completed, upon a signal being received by the operator from Mr Savin a powerful current of electricity was transmitted through the conducting wires, communicating with each of the charges, and the same instant the whole simultan- eously exploded with one loud report, at once hurl- ing down and completely shattering a mass of rock computed to weigh not less than 40,000 tons. The effect of the explosion, as seen and heard by those who had the rare advantage of witnessing it from a near and a safe position, was grand in the extreme, and the result very forcibly demonstrated th fact of the superiority of mind over matter. Although massive pieces of rock were projected to very great distances no accident happened, we are glad to say, to any of the spectators who wit- nessed the explosion, amongst whom were several gentlemen well-known in scientific circles.

MANCHESTER AND MILFORD RAILWAY…

[No title]

----------CORRESPONDENCE.

-.------------UNIVERSITY AND…

t THE WATER QUESTION, &c.

THE CARDIGANSHIRE ASSIZES.

------.------------_.----THE…

Family Notices