370 THE rKOGRp:ss OF gp:(>graphical knowledge. 



Under all other ordinary conditions it is maintained hy Canadian sur- 

 veyors that, although both time and l-ahor may l)e saved on the held 

 operations, the resulting maj) can never attain the same standard of 

 accuracy in detail that distinguishes good topographical illustration of 

 the usual variety of natural features. I am, of course, now speaking- 

 of geographit-al surveying as an art, not of mere g-eographical exploi- 

 tation. In the lattei" case doubtless every traveler who can ''pull the 

 string'' in these days can add innncMisely to the personal interest of his 

 journeys by his illustrations of them. Hut I would earnestly impress 

 upon all travelers that if they desire those illustrations to be of any 

 use for geographical com})ilation it is aI)S()lutely necessary to know 

 the point from which they were taken and the direction of the \ iew. 



BAROMETRIC RECORDS. 



Once again, too, would 1 warn travelers of the utter uncertainty of 

 all classes of barometric; determinations for altitude. Very little has 

 been done in recent years toward improving- instruments of the ])aro- 

 mctric class, and meteorological science has not yet taught us how to 

 deal with the constant variations in air ])ressure produced over local 

 areas by changeable weather. There are some countries where l)aro- 

 metric records can hardly be regarded as offering a clue e\en to 

 differential heights. It can not be too often insisted on that the 

 determination of the relative heights of mountain peaks and of the 

 local value of refraction by means of the theodolite is as much the 

 duty of the triangulato? as is the fixing of those peaks in position for 

 the use of the topographer. Fi'om these, again, the altitude of posi- 

 tions in the plains can be safely determined by small instruments of 

 the clinometer class without resorting to the barometer at all, although 

 it may still be necessar^^ to ascertain the value of one initial (or final) 

 point Avhich nuist be determined l)y many observations spread over a 

 considerable length of time and synchronous with another set of obser- 

 vations determined at sea, or some already known, level. This, of 

 course, will occur only when a new geographical area is opened up to 

 survey at some distance from the sea. 



UNIVERSAL MAlT'INi;. 



It will l)e i'ememl)ered that a scheme was set afloat some years ago 

 by Dr. Penck, the eminent (lerman geogra})her, for the mapi)ing of 

 the whole world on the seale of one-millionth, which is very nearly 

 e(|uivalent to the scale of It) miles to 1 inch. Substantial ])r()gress has 

 now be(Mi made in supi)ort of this scIkmuc^ by English map makers, 

 especially in India, wh(>re all the traiis])oi-d(M- countries \vhicli ha\'e 

 lallen geographically into tlu^ hands of Indian sur\eyors an* now ]>eing 

 mapped on this scale. In the commencement of all great colonial 

 ."urvey schem \s it is much to be hoped that this project for one 

 homogeneous and universal map will not be lost sight of. 



