MIRAMICHI RIVER 



3841 



MIRROR 



named because of the legend that it was the 

 work of a fairy of the same name in medieval 

 romances. C.R.M. 



MIRAMICHI RIVER, mirahmishee', the 

 largest river in New Brunswick, except the 

 Saint John. It is a small stream, for it is only 

 135 miles long from its mouth to the head- 

 waters of its principal tributary. The Mira- 

 michi is famous, not for its size but for its fish ; 

 it is one of the greatest salmon streams of the 

 world, and is visited every year by hundreds 

 of sportsmen. The whole Miramichi basin, 

 which covers a little more than 5,000 square 

 miles, is in fact a paradise for hunters. It has 

 never been thoroughly explored, and moose, 

 caribou, deer, bears, wolves, foxes and many 

 smaller animals range the forests. In some 

 sections the advance of the lumberman, how- 

 ever, has driven away the game. Pine woods 

 line the banks of the river and its tributaries, 

 and lumbering is now an important' industry. 



From its mouth in Miramichi Bay, an arm 

 of the Gulf of Saint Lawrence, the river is 

 navigable for large vessels as far as New- 

 castle, a distance of thirty miles. Up to this 

 point it is practically an arm of the sea. About 

 five miles above Newcastle the river proper 

 comes to an end, and divides into the North- 

 west Miramichi and the Southwest Miramichi. 

 The latter is the head stream, some of its 

 numerous branches extending within a few 

 miles of the Saint John River, in the western 

 part of the province. By short portages be- 

 tween these branches and the tributaries of the 

 Restigouche and the Saint John the Indians 

 could reach any part of the present province 

 in their canoes. The same possibility exists 

 to-day for the sportsman and camper. H.V.B. 



MIRROR, mir' er. Every person makes daily 

 use of a mirror or looking-glass. Any smooth 

 surface which is capable of reflecting the rays 

 of light that fall upon it is a mirror. The or- 

 dinary looking-glass is a pane of glass coated 

 on the back with a layer of silver or mercury. 

 Mirrors are used not only for household and 

 decorative purposes, but also in a great number 

 of scientific and other instruments, such as mi- 

 croscopes, telescopes, searchlights, and the like. 

 The action of the mirror is based on the general 

 laws of reflection of light, which are: (1) the 

 incident rays, the normal and the reflected rays 

 are all in one plane; (2) the angle of incidence 

 is always equal to the angle of reflection. 



The mirrors used in our houses or public 

 places are plane mirrors, that is, mirrors having 

 plane surfaces. When you stand before such a 

 241 



mirror, your image is of the same size as your- 

 self, and appears as far behind the glass as you 

 are in front of it. The image is, however, re- 

 versed. Thus, when you raise your right-hand, 

 it appears to raise its left hand. Let us see how 

 images are formed in a plane mirror. In Fig. 1 



Construction of an image in a plane mirror. 



let MN represent the mirror and AB the ob- 

 ject. An observer placed at E will see the 

 image A'B' situated behind the mirror. That 

 image is formed in the following way: From 

 the point A rays of light are sent out in all 

 directions. Some of these strike the mirror at 

 the point D and are reflected towards DE. To 

 the observer at E the point will appear to lie 

 in the direction EDA'. Other rays will strike the 

 mirror perpendicularly at the point P and will 

 be reflected back in the direction PA. To an ob- 

 server at E the point A will appear to lie along 

 the line APA' . The image of A will therefore 

 be found at the intersection of these two lines, 

 that is at A'. In the same way the image of 

 B will be formed at B' , and those of all the 

 intermediate points between A and B will lie 

 between A ' and B ' . 



A concave mirror is a portion of the inner 

 side of a sphere. The center of the sphere, of 

 which the mirror is a portion, is called the cen- 

 ter of curvature. The line connecting the mid- 

 dle of the mirror with the center of curvature 

 is called the principal axis. Any straight line 

 from the mirror through the center of curva- 

 ture is called a secondary axis. When rays of 

 light parallel to the principal axis strike a con- 

 cave mirror, they are reflected in such a way 

 that they meet at a single point, called the 

 principal focus. The principal focus is situated 

 on the principal axis, halfway between the 

 mirror and its center of curvature. Let us see 

 how an image is formed in a concave mirror. 

 In Fig. 2 let MN be the concave mirror, and 

 AB the object. The line PC is the principal 



