71 



Illumination was then explained. French map-makers assumed 

 that the light came fi'om the left hand top-corner, and inserted 

 the shaded parts accordingly. By such a procedure a beautiful 

 map could be produced, but from it calculations were impracti- 

 cable. Maps could be made which embraced both styles of 

 illumination. In order to make a map by which precise and 

 reliable data could be obtained Contoiu' Lines were necessary. 

 These were explained at length ; the lecturer observing that 

 they represented horizontal lines at various levels, such as one 

 might suppose were tide marks. Each was of com'se an endless 

 line, and they were usually made at regular intervals. That 

 such maps admitted of absolute calculation was demonstrated 

 by drawings on the black board. A Swiss map constructed on 

 a scale of 3 inches to the mUe, and said to be the most accurate 

 map in the world was refeiTed to as manifesting the principle. 

 Contour maps do not give pictures, and if the lines are cut as 

 they must necessarily be in maps of limited parts of the surface, 

 information is wanting. Shading is now combined with contours, 

 so that the shape of ground is more readily apparent to the eye. 

 By means of contour lines sections can be drawn, slopes can be 

 read off, exact heights can be fixed, and it can be ascertained 

 whether any one point is visible from any other point. Captain 

 Wilkinson had a large and valuable collection of militaiy and 

 other maps to illustrate his lecture, and ample use was made of 

 the black board. 



In subsequent remarks, Captain Wilkinson said that in the one 

 inch Ordnance Map the contours were not at regular intervals ; 

 and this was undoubtedly an objection. The English Govern- 

 ment had not produced any map less than one inch to the mile. 

 The six Northern counties had been completed on the scale of 

 six inches to a mile. The work was only being slowly prosecuted, 

 and this fact, as well as the dearth of authoritative charts, was 

 due to the meagre amount voted for Survey purposes. 



FLORIDA. 



By H. W. PARKINSON. November 16th, 18S6. 



After noting the geographical position of Florida, and making 

 a brief reference to its history, Mr. Parkinson said that the 

 general impression derived from the works issued fi-om the 

 Immigration Bureau at Tallahassee was that Florida was little 

 short of paradise, that it was almost a wilderness of wild flowers, 

 cabbage palms, stately rivers, fertile lands, silver springs and 



