MINE TIMBERING.
The square system of timbering, in use in most of our large mines on the Pacific coast, was first introduced in Australia by Mr. W.H. Patton, who adopted it in the Broken Hill Proprietary mines, although it does not seem to be so satisfactory to the people there as to our miners, who are more familiar with it. The accompanying description and plans were furnished by Mr. Patton to the report of the Secretary of Mines for Victoria:
"The idea is supposed to have originated in the German mines, but in a crude form. It was introduced among the mines of the Pacific coast of America some 20 years ago, by a gentleman named Diedesheimer. Its use there is universal, and experience has evolved it from the embryo state to its present perfection. The old system and its accompanying disadvantages are well known. A drive would be put in for a certain distance, when it had to be abandoned until it could be filled up with waste material and made secure. This process entailed much expense. The stuff had first to be broken on the surface, then sent below, trucked along the drives, and finally shoveled into place. Ventilation was impaired and the drives were filled with dust. The men worked in discomfort, and were not in a condition to perform a full measure of labor. Under the system as adopted in the Proprietary mine, these disadvantages disappear. The cost is one-third less, ventilation is perfect, and every portion of the faces are accessible at all times. Sawn timber is used throughout; the upright and cross pieces are 10 inches by 10 inches, and stand 4 feet 6 inches apart; along the course of the drive, the cross pieces are five feet in length, and the height of the main drives and sill floor sets are 7 feet 2 inches in the clear. In blocking out the stopes, the uprights are 6 feet 2 inches, just one foot shorter than those in the main drives. The caps and struts are of the same dimensions and timber as the sill floor. The planks used as staging are 9 inches by 2½ inches; they are moved from place to place as required, and upon them the men stand when working in the stopes and in the faces. A stope resembles a huge chamber fitted with scaffolding from floor to roof. The atmosphere is cool and pure, and there is no dust. Stage is added to stage, according as the stoping requires it, and ladders lead from one floor to the other; the accessibility to all the faces is a great advantage.
If, while driving, a patch of low grade ore is met with, it can be enriched by taking a higher class from another face, and so on. Any grade can be produced by means of this power of selection. Opinions have been expressed that this system of timbering is not secure, and that pressure from above would bring the whole structure down in ruins. But an opinion such as this is due to miscomprehension of the facts. If signs of weakening in the timbers become apparent, the remedy is very simple. Four or more of the uprights are lined with planks, and waste material is shot in from above, and a strong support is at once formed, or if signs of crushing are noticed, it is possible to go into the stope, break down ore, and at once relieve the weight."
TRANSIT IN LONDON, RAPID AND OTHERWISE.[1]
By JAMES A. TILDEN.
The methods of handling the travel and traffic in the city of London form a very interesting subject for the study of the engineer. The problem of rapid transit and transportation for a city of five millions of inhabitants is naturally very complicated, and a very difficult one to solve satisfactorily.
The subject may be discussed under two divisions: first, how the suburban travel is accommodated, that is, the great mass of people who come into the business section of the city every morning and leave at night; second, how the strictly local traffic from one point to another is provided for. Under the first division it will be noted in advance that London is well provided with suburban railroad accommodation upon through lines radiating in every direction from the center of the city, but the terminal stations of these roads, as a rule, do not penetrate far enough into the heart of the city to provide for the suburban travel without some additional methods of conveyance.
The underground railroad system is intended to relieve the traffic upon the main thoroughfares, affording a rapid method of transportation between the residential and business portions, and in addition to form a communicating link between the terminals of the roads referred to. These terminal stations are arranged in the form of an irregular ellipse and are eleven in number.