240 



KNOW 1.1 



|IM . 1912. 



photiiKrapliiiiK nl In in.; iibjrii,. I in- ,i|)p,ii.iiiis i?, slimvii iti 

 I'iKtire 2f»S which we owe to l\\r C(iiiili-sy of Messrs. Watson 

 and Sons. Insidf, .i snrfacosilvi-rcd niiiror set at an angle of 

 45' proiects the iniaKe of the ohji-cl on to the ground glass 

 screen seen on the left hand of the illnstrntion. The shutter 

 of tlie dark-slide can be drawn as soon as the mirror is set. 

 When the release is worked the mirror covers the screen and 

 the exposure is made and terminated by the falling of a flap. 

 The exposure can be made very short if desired, but as a rule 

 in practice it is about one or two seconds. The photograph 

 which is reproduced in Figure 2()7 was taken on an Imperial 

 Rapid Plate .ind the exposure was half-asecond, the light 

 being obtained from a Duplex oil lamp. To set the shutter 

 for timcexpoAures, it is manipulated in the ordin.iry way and 

 then the lever C. shown in Figure 268, is turned so that it 

 points vertically to H. On pressing the release, the shutter is 

 opened and will remain so until the lever is brought back to A. 

 It will be obvious that this excellent little camera can be 

 used on many occasions where there is no need for instantaneous 

 work and it will be a convenience to those who are accustomed 

 to use an ordinary camera that the focusing screen is vertical. 

 Messrs. Watson & Sons are to be congratulated on the produc- 

 tion of this simple, effective, and compact piece of apparatus. 



yUEKETT MICROSCOPICAL CLL'B.— On April 23rd, 

 Mr. A. W. Stokes exhibited and described several methods of 

 adapting electric lighting to microscope illumination. In one 

 case the lamp, enclosed in a metal tube open at one end, was 

 fixed to an adjustable arm attached to the stand. When once 

 focussed on the object it remains so. If an ordinary supply of 

 current was not available, the use of small pocket batteries 

 was recommended. These gave four hours' light at a cost of 

 fourpence, and the cell was easily renewed. 



John Stevens, F'.R.M.S., read ".A note on Notontinata 

 gif>antcit Glascott." This rotifer, a true parasite, is only found 

 in the ova of water-snails, and the comnumicatiou was a series of 

 notes of observations made in June, 1911. 



Dr. Duncan J. Reid discussed " Illumination in critical work 

 with the microscope." The subject was treated under the 

 following heads : — The most suitable light, collecting lenses, 

 the principles of correct illumination ia), as regards the field 

 and {!)), filling of the objective with light, condensers, distance 

 of lamp from mirror, critical and non-critical illumination, 

 working aperture and general arrangement of light and 

 apparatus in high, medium, and low power work. 



C. D. Soar. F'.R.M.S., exhibited coloured figures of the fifty 

 species of Arrhciiiints recorded in the British Isles. 



ORMTHOLOGV. 



By Hugh Boyd Watt, M.B.o.U. 



WINTER MOVEMENTS OF THE GANNET IN THE 

 OUTER HEBRIDES.— Mr. Robert Clyne, lightkeeper at 

 the Butt of Lewis, in a recent article in The Glasnozc Herald 

 has given a vivid sketch of the movements of this great bird 

 " midst furthest Hebrides." He writes : — " Gannets are never 

 altogether absent from our shores, though they are rarely seen 

 during the three winter months. Borne west and north by 

 south-east gales, they were seen by mid-February passing the 

 Butt of Lewis, flying out into the North Atlantic, having been 

 absent from the locality for only a few weeks. Their annual 

 extraordinary procession up the Minch, round the north of 

 Lewis, and out in a southwesterly direction to their breeding 

 haunts — St. Kilda principally — is not due until about the 

 middle of March. .-At the Butt of Lewis they all appear as 

 coming up the Minch, but doubtless the majority will collect 

 from the North Sea. rounding Cape Wrath, keeping well, as is 

 their habit, to the contour of the land, till near the Lewis coast 

 they converge with others into one continuous stream. 

 Hugging the land at the extreme north end of the Lewis, 

 many pass through a narrow channel — a veritable gannet 

 highway, for over it flocks pass all summer going to and from 

 their feeding groimds." 



SUCCESSFUL PROTECTION OF BIRDS.— We gather 

 the following satisfactory items from the recently-issued 



Annual Ripnrl for the yi-.ir I'M I mI tin- l<ip\al >ociety for the 

 I'roleclionof Birds. At one of the few remaining breeding-places 

 of the ("hough, eleven pairs were seen instead of only three 

 pairs as was the case when the work of protection by a 

 watcher was started ; and in the Shetland Islands the (ircat 

 Skua h.id increased largely in munbers, while Richardson's 

 Skua was now plentiful (Mr. E. G. B. Meade- Waldo). There 

 were now at least eight pairs of kites where nine years ago 

 oidy two pairs and an odd bird existed. In a certain area in 

 tile same period of time. Buzzards are estimated to have 

 increased from forty pairs to seventy pairs. Ravens had done 

 exceedingly well, and Barn (Jwls were again becoming 

 numerous (Rev. D. Edmunds Owen). An extraordinary in- 

 crease in the winter flocks of (Goldfinches and Siskins in 

 Scotland was reported by Sir Herbert Maxwell. 



ARRIVAL OF SUMMER-BIRDS: A COMPARISON.— 

 The following list gives the dates of the arrival of some of our 

 earliest summer visitants up to the end of April this year. 

 The English dates are mostly from the columns of The Field 

 and the Scottish ones are from a report made by Mr. John 

 Paterson to the Natural History Society of Glasgow. The 

 list is confined to birds occurring in both districts, and there- 

 fore many kinds known in England are not included in it. In 

 a general way it confirms what is known as to the differences 

 consequent upon the geographical situation of the two districts, 

 but reports the White Wagtail and Corncrake are earlier in 

 the North than in the South. 



NEW LIST OF BRITISH BIRDS,— Messrs. Witherby 

 & Co. have just published " A Hand-List of British Birds," 

 giving a detailed account of the distribution of each bird in 

 the British Isles, and a general account of its range abroad, 

 together with details of the occurrences of rare species. The 

 Haud-List is the joint work of Messrs. E. Hartert, F. C. R. 

 Jourdain, N. F. Ticehurst. and H. F. Witherby. 



I'llO r()C.R.\lM)\". 



By ICpg.vk Sk.mok. 



EXPOSIRE TABLE FOR JUNE.— The calculations 

 are made with the actinograph for plates of speed 200 H. and 

 D., the subject a near one, and lens aperture F.16. 



Reiiitirks. — If the subject be a general open landscape, take half 

 the exposures given here. 



