74 SECTIONAL ADDRESSES. 



Traverses are made, by bicycle mainly, with (a) the prismatic or 

 pocket compass, for direction ; {b) cyclometer, or measuring wheel, for 

 distance ; (c) aneroid barometer, with thermometer attached, for altitude 

 and temperature ; and {d) watch, for time. 



On lea^'ing a camp all four observations are taken, but instead of the 

 traverse being tabulated in columns as usual — which method gives no 

 graphic idea of the orientation of the traverse — the graphic method is 

 used. This shows at once the direction being taken, for the bearing of 

 each line is roughly plotted in the field-book, as to direction and length, 

 and a continuous traverse obtained, in which, in its relative position, each 

 natural feature is placed. The observations embrace features such as 

 sites of camps, and prominent landmarks, edges of stream flats and 

 banks, water-levels, gullies, tops of rises or ridges or plateaux, edges of 

 plateaux or hills, huts, villages, outcrops of rocks, showing dips, strikes, 

 characters and any special features. All four observations {a- — d) are taken 

 at each of such places, except the occasional omission of that for time 

 when stoppages are frequent. But at places where the stoppage is for 

 ten minutes or more the time observation also is taken on leaving, for the 

 purpose of correction for altitude because of change in air-pressure. 



As far as possible samples of the gravels of all streams, as well as the 

 loam beside outcrops of quartz reefs and dykes, and the material from 

 road-gutters or paths, are panned, and concentrates of heavy minerals 

 obtained. (In certain types of country panning is the most useful aid to 

 prospecting, not only in the discovery of gems and stable metallic minerals, 

 such as native gold, platinoid minerals, oxides of tin, thorium, titanium, 

 iron, chromium, tungsten, and manganese, but also of many rock-forming 

 minerals, which indicate the probable character of the rocks at the spot, 

 or in the basin of the stream tested.) Specimens of rocks and samples 

 of quartz are collected for reference, museum purposes, microscopic 

 examination of thin sections, or testing by assay, analysis, or other 

 methods. Coal, lignite, limestone, and other economic rocks, brick and 

 pottery clays, and pigments are sought ; also fossils, which, if found, are 

 used to determine the age of the strata associated with them. 



In addition to the general observations indicated, notes are made of 

 the colour, kind, and thickness of soil, the nature of the vegetation, size 

 and kind of stream and gravel, and measurement of volume of water — 

 when there is opportunity, and if of possible economic value, with regard 

 to domestic supplies and possible hydro-electric power and irrigation. 



It will thus be seen that the geologist in a new country, by taking the 

 opportunity to make the observations mentioned in the last section is 

 helping his colleagues in other departments by collecting evidence of 

 probable future value. 



On the completion of several traverses roughly parallel with one 

 another, particularly if they have been made across the strike of the 

 rocks, a large amount of useful geological and topographical information 

 is available. From this a map can be prepared, with possibly a connection 

 with some definitely fixed point, and on it all natural features observed 

 can be shown, sufiiciently near to accuracy to serve fully the purpose of a 

 map to a comparatively small scale. 



To this can be added the geology and mineral occurrences, the various 



I 



