Synopsis
Excerpt from Mining Tables: Being a Comparison of the Units of Weight, Measure, Currency, Mining Area, of Different Countries; Together With Tables, Constants Other Data Useful to Mining Engineers and Surveyors
The compilation of the short section on thermal units dis closed the existence of much confusion in text-books, largely due to the various thermometric scales in use. There is also an absence of any agreement as to the terminology of the units. For instance, as Swinburne points out, there is no name for the unit of difference of temperature, degree being almost as primitive as mark or notch.l Again, the British thermal unit or pound-degree (fahrenheit) has no name; and calorie may mean either the gramme-degree (centigrade) or the kilogram-degree (centigrade). In regard to specific heat, thermal capacity, calorific power and thermal efficiency, there is a lack of authoritative definition such as has fixed for all time the electrical units.
The mining data collected in Part V. Refer rather to the physical properties of ore-bodies than to the mechanical devices for their extraction. Thus, hoisting, pumping and ventilation, to which many special treatises have been devoted, are not dealt with. On the other hand, tables are given by which the calcu lation and valuation of ore-reserves are assisted and simplified. The latest information regarding the question of underground temperatures is summarised. The various methods in use in different countries for expressing gold ore values and for stating copper prices are compared. Finally, there is a section on mining areas which has been carefully compiled from the laws now in force in the Colonies and in foreign countries where mining is carried on.
The data relating to surveying which comprise Part VI. Include a description of the conventional methods in practical use for the coordination of survey points, also a description of the use of the tacheometer, and a table for the calculation of heights and distances from tacheometric readings.
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