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The Practical Miner's Guide: A Treatise on Mine Engineering; Comprising a ...
Δεν υπάρχει διαθέσιμη προεπισκόπηση - 2017
The Practical Miner's Guide: A Treatise on Mine Engineering
Δεν υπάρχει διαθέσιμη προεπισκόπηση - 2019
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Σελίδα 186 - Through the interior of the tube a column of water is sent down to the bottom of the boreholes, which water, rising in the annular space between the exterior of the hollow boring rod and the sides of the bore-hole, creates an ascending current which carries up the triturated soil : the boring tube is then worked like an ordinary boring rod ; and as the material is acted upon by the tool at the lower end, it is immediately carried up to the top of the bore-hole by the ascending current of water. It...
Σελίδα 172 - There is another class of injuries resulting from defective ventilation to which miners are exposed. The circumstances producing these injuries are slow in operation, and from their effects being disease, and not immediate and sudden death, their existtence has been little considered.
Σελίδα 186 - ... the strata which have to be encountered. The diameter of the tool is larger than the diameter of the tubular rod, in order to form around it an annular space through which the water and the excavated material may rise up. The upper end of the hollow rod is connected with a forcepump by jointed or flexible tubes, which will follow the descending movement of the boring tube for an extent of some yards. This boring tube may be either worked by a rotary movement with a turning handle, or by percussion...
Σελίδα 172 - These effects are the result of an inadequate supply of air, which thus becomes vitiated and unfit for breathing, on account of its having lost its due proportion of oxygen, which is replaced by the formation of carbonic acid. This gas has its sources...
Σελίδα 66 - AC in d and e; then take the distance ed in your compasses, and setting one foot on the brass pin at the beginning of the chords on your scale, observe how many degrees the other foot reaches to, which will be 4° 15
Σελίδα 172 - ... which has become vitiated and unfit for breathing, on account of its having lost its due proportion of oxygen, which is replaced by the formation of carbonic acid. This gas has its sources in respiration, the lights of the mine, the decomposition of small coal in the goaves (cavities of the roof), and of timber in the workings.
Σελίδα 13 - The sum of the three angles of every plane triangle being equal to half a circle, or 180 degrees, it therefore follows that if either acute angle, in such triangle, be taken from 90°, the remainder will be the other acute angle, or the complement. The supplement of any angle is what that angle wants of 180°: hence the supplement of any one angle is always equal to the sum of the other two. A few other properties of right-angled triangles may be worthy of notice, viz.: when the angle opposite the...
Σελίδα 63 - ... multiply them respectively by the length of the hypothenuse, reduced into fathoms and parts (if any), and place them in their proper positions until the whole has been calculated ; then take the sum of the bases north and south one from the other, and the sum of the perpendiculars east and west one from the other ; the perpendicular remainders will show the east and west line, and the bases the distance the dialling has extended north or south of that line. The work is now brought to that case...