Show THE BLASTING OF BLOSSOM ROCK yesterdays telegraphic dispatches brought the news of the blowing up on saturday last of or blossom rock bock in san Fran francisco cheo harbor this rock has prove dof much annoyance and danger to shipping and the success which has attended its removal must be very gratifying to the people of ot that city and especially to the engineer who invented agthe the plan to remove it blossom bock rock was six feet below the surface of the water at low tide and the awater water rolled over it in powerful swells and great force its position was such gas as to render the work of removing it both sooth dilli difficult cult and dangerous about four months ago col van a civil engineer eug ineer devised a plan which he thought would be successful it was a difficult undertaking to perform one that must be watched with the most intense care for one false step or mishap would prove ruinous and destructive and involve the loss of many lives the first work to be done according to his plan was to make a careful survey of the rock ascertain where it dipped in and where it projected so that in the work of excavation afterwards to be accomplished sufficient of a space might remain to resist the pressure of the water this was carefully done and efrom from it plans were drawn of the rock the next work was to construct a water tight copper dam on the rock and around that part of it through which tile tiie shaft was to be sunk eunk this was found to be most difficult As already stated the water rolled there in great force in large swells and being interrupted by the rock naturally gave it more force in passing over it than in any other portion of the bay the coffer dam was first put in its place and then a scow was built around it into which about two hundred and fifty tons of stones were thrown the dam was lined around with bags of sand to more effectually keep out the water and when this was complete an iron turret was placed inside of it this turret was im bedded or sunk in the rock a distance of three feet and closel closely yand and thoroughly cemented at its place done the work of excavation or sinking the shaft commenced A platform was erected on the rock fifty six feet in length and about twenty in width on this an engine and a complete hols hois hoisting tin apparatus was placed at one end an and d N at the other a shanty was erected containing six sleeping apartments and a kitchen which was also used as an on eating room by the workmen when the shaft had bad been sunk sufficiently to permit the work of excavation to be extended to either side the work was considered fairly begun and from that time forward it was pushed with all the despatch possible when the shaft had reached a certain depth a email small cylinder was placed inside the original turret extend ting jing ing down into the shaft which made the hoisting of the ballast from below more ore one convenient the plan for the removal of the rock can n be best understood in this way the object was to scoop out the center prodie ing ng a cavity inside measuring in the clear from the highest point to the bottom twenty nive five leet and leaving a crust or stratum of about six feet thick to resist the pressure of the water while the work was in progress this crust or stratum to be blown up by powder when the remainder of the work inside had been completed to do this however was not only difficult but perilous and involved the heaviest responsibility it required the closest attention and the exercise of more than ordinary skill As the work progressed and the excavation became larger the crust of rock left standing would naturally ba b come weaker and more likely to cave in gln gin in order to prevent this pillars of orrock rock were left standing at short intervals from each other until the tho limits of six feet were everywhere reached then it became necessary to move these pillars away before athis this was done uprights of heavy timbers were set thickly around the cavity to supply their place and in this way all fear of I 1 the me roofing was obviated the hight bight of the highest pillar was twenty nine feet and the lowest mur four feet the space excavated measured about one hundred and forty by sixty feet the rock was sandstone and porous and the water dripped through A steam pump was employed to keep the shaft dry twenty three tons of powder was used in the explosion about half of this quantity was in english ale barrels double coated with a heavy pitch varnish inside and outside so as to make them water proof the other half was placed in seven boiler tanks which were of wrought iron firmly bolted together As they contained each more powder and their jex explosive plosive force was much more powerful than the barrels they were placed where the thu distance from the top to the bottom of the excavation was greate greatest Bt the barrels were placed close to the side of the excavation near the junction of the arch or roof with the floor A perforated piece of gas pipe two and a half feet in length charged with fine gun powder run into each barrel from the end and a piece six feet long into the boilers charged in the same way these different tubes were connected with insulated electric wires which passed from one barrel to another while the end in each tube consisted of a fulminating cartridge which when reached by the electric spark exploded and ignited the powder in the tube this tube in turn exploded and communicating with the powder in the barrel boiler caused them to explode also to make the connections of the tubes with the barrels perfectly watertight water tight rubber washers were placed between each connection and the insulated electric wires connecting the barrels were encased in a gutta percha hose so as us to keep beep it perfectly dry this wire was drawn up through a tube in the shaft and was placed on board a bark about one thu thousand feet from the nock rock there it was connected with an electric battery the water acted as tani tamping ping the coffer dam tiam having been removed to permit it to fill up the excavation fears were entertained by many people respecting the effects of the explosion of such an imm immense e n se quant quantity ity of powder but the tho telegraphic h report baya saya there was no perceptible i jar ar only a deep thud accompanied t the e b last blast A body of water was thrown to the height of a hundred feet the aita alia california from which we have gathered the foregoing particulars speaks of the achievement as a great triumph of engineering skill and one that reflects the highest honor on colonel one I 1 von t |