558 



KNOWLEDGE & SCIENTIFIC NEWS. 



[October, igo6. 



The "Unilens," 

 A Simple Telescope. 



It is curious how, occasionally, some very simple ap- 

 plication of known principles is broutjht forward as a 

 practical appliance, which, for some 



reason, has never before been tried, 



or, rather, widely applied, to th( 

 purpose. This is the case with the 

 " Unilens," lately patented by Major 

 Baden-Powell. It consists merely 

 of a convex lens, 2i inches dia- 

 meter, having a focal length of 

 about 6 feet. This, mounted tem- 

 porarily at the end of a stick, 

 enables an enlarged view of dis- 

 tant objects to be obtained, the 

 maximum magnification being about 

 4 diameters. Considering the ex- 

 treme simplicity and low cost of 

 the appliance, it should form a 

 most handy glass for all ordinary 

 purposes, comparing favourably as 

 regards power with the cheaper 

 opera and field glasses. As now 

 designed, the glass is mounted on a 

 metal base from which projects a 

 small screw, and it may thus be 

 readily affixed to any walking-stick, 

 cKx., while, being so small and flat, 

 it can be carried in the waistcoat 

 pocket. 



Though there may be no special novelty in this appli- 

 ance asan optical instrument, yet as a practical means 

 of observation it should prove of great value to almost 

 all observers of Nature. As an astronomical instru- 

 ment it can, of course, hardly claim a high place, yet 

 so simple and portable an apparatus has its uses. We 

 know how useful even a low-power opera-glass can be 

 in looking on the heavens, and many features are thus 

 cle.-irlv shown which are not perceptible to the naked 



eye. For instance, on looking at the Pleiades through 

 the " Unilens " eight stars can be discerned, although it 

 is seldom that more than six arc visible to the unaided 

 vision. The naturalist will certainly find this portable 

 glass of great assistance in watching birds and beasts 

 even at a few yards off, at which distance thev are 

 greatly magnified. The botanist, too, may find it of 

 use in examining plants out of reach. 



An Easy Position. 



•Unilens " at FuU Focus. 



Tliis glass has the great advantage of always being 

 in focus. The further it is held from the eye the greater 

 is the magnification. But if it be merely held in the 

 hand at arm's length it is a great aid to natural sight, 

 and is most useful in the theatre or even picture gallery 

 or tathcdral. When on the end of a stick, and the stick 

 held at arm's length, that is to say, when the glass is 

 approaching six feet from the eye, objects are seen at 

 the greatest magnification, although they then begin 

 to get slightlv blurred. 



It need hardly be said that such a glass 

 is not suitable to all eye-sights. Those 

 ■ lightly affected by myopia, or short-sight, 

 do not see well through the single lens. 

 But if these persons use a concave eye- 

 glass as well, not only will they see clearly 

 through the " Unilens," but will improve 

 their sight under ordinarx' circumstances by 

 the habitual use of the eye-glass. This 

 little appliance is being placed on the market 

 by Messrs. Newton, of Fleet Street. 



Nature-Study : A Field Lesson at Werribee 

 Gorge, Bacchus Marsh. (Melbourne : Govcrn- 

 inint Prt'SN, K)<)()l. — This well illustrated .'ic- 

 count of a visit of pupils to the locality men- 

 tioned is published as a supplement to ihe 

 Melbourne Eliication and Teachirs' Aid, and 

 shows that the \'ictorian Government is 

 thoroughly awake to the necessity of going 

 to the original source, if education in natural 

 >cience is to be of any value. The members of 

 the partv were fortunate in having presented 

 to them some excellent specimens of ancient 

 ijl.-iciation, 



