March 19, 1903 J 



NA TURE 



473 



former days the bird-life appears, however, to have been 

 ■even more abundant than at the present day, this being 

 especially the case with regard to kittiwakes, which were 

 ■once found in thousands where there are now hundreds. So 

 numerous, indeed, were these birds that there is a record 

 of the heaps of twitch left in a field on a Saturday to be 

 carted on the Monday having been carried off in the mean- 

 time bv the gulls for nest building. The usual ruthless 

 massacres of the old days were, however, responsible for so 

 reducing the numbers of these birds that they were well- 

 ;nigh exterminated by the time the Protection Acts once 

 more gave them a chance. 



After referring briefly to the puffin and the razorbill, 

 accompanying his notice of the former by an excellent figure 

 ■of a young bird (herewith reproduced), the author treats 

 in considerable detail of the breeding habits and eggs of 

 the guillemot. Attention is called to the number of young 

 •ones and eggs which are destroyed by falling down the cliffs 

 when the birds are suddenly frightened, the author express- 

 ing his belief that a guillemot will intentionally roll its 

 ■egg from the ledge on which it rests if she thinks it is about 

 to be carried off. The remarkable variation displayed by 

 guillemot eggs naturally claims a share of attention, 

 although the author confesses that he is unable to give any 

 reason for the phenomenon. In this connection it may be 



Pig. 2. — A descent in search of eggs. (From the " Birds 

 ■ if Bempton Cliffs.") 



mentioned that a magnificent series of these eggs, showing 

 nearly all the chief types of variation, has recently been 

 placed on exhibition in the Natural History Museum. 



Cliff-climbing in Yorkshire is always effected by means of 

 ropes, the author describing it as the most delightful and 

 exciting form of gymnastics. Judging from the illustration 

 here reproduced, some of our readers might think it a trifle 

 too exciting. At the present time from 300 to 400 eggs 

 are collected daily during the season, the total take being 

 about 130,000. In spite of this drain the numbers of the 

 birds annually increase. The price of the eggs varies from 

 twelve to sixteen a shilling, abnormally marked specimens 

 fetching from 2d. to 7s. 6d., or even more, each. R. L. 



NO. 1742, VOL. 67] 



A 



A NEW BINOCULAR. 



NEW form of prismatic binocular, styled the " Service," 

 has recently been issued by Messrs. J. H. Dallmeyer, 

 and there are many interesting features about it for which 

 special advantages may be claimed. As a rule, binoculars 

 consist of two independent optical trains in separate cover- 

 ings, either hinged together to allow for the different 

 gauges between the separation of human eyes, or made in 

 different sizes to suit these various distances. In the present 

 form the whole optical arrangement is enclosed in one cover, 

 and in consequence of this, six out of the eight prisms em- 

 ployed and the two objective sliding tubes can all be fixed 

 rigidly to one frame, thus ensuring maintenance of adjust- 

 ment and strength in adverse circumstances. 



The separation of the eye-pieces is secured by a screw 

 adjustment situated between them, by which each eye-piece 

 with one prism slides in strong grooves in a lateral direc- 

 tion. For any one individual this adjustment is constant, 

 so that when once the correct position has been attained 

 a permanent mark can be made, and this position quickly 

 regained at any other time ; the maximum separation 

 between the centres of the eye-pieces is 70 mm. and the 

 minimum 55 mm., so plenty of latitude is available for 

 abnormal eyes. 



There is another screw adjustment for the ordinary focus- 

 ing, and one of the eye-pieces can be separately adjusted by 

 means of a graduated spiral movement in case the observer's 

 eyes are not similar. All these different manipulations can 

 be easily made when only one hand is available, and the 

 whole mechanism can be fully exposed for cleaning the 

 optical surfaces by simply taking out four screws which in 

 no way interfere with any of the adjustments. 



Constructed chieflv of magnalium, and in parts of gun- 



metal, the glasses are light in weight, and it is claimed 

 that they are smaller, power for power, than any other 

 prismatic glass yet made. There are five sizes on the 

 market varying in magnifying power from four to twelve 

 times, the former weighing thirteen and the latter sixteen 

 ounces ; the smaller sizes are suitable for theatre or night 

 use. 



SEISMOLOGICAL NOTES. 



THE last publication of the Earthquake Investigation 

 Committee of Japan, issued this year, is of special 

 interest to those engaged in seismometry. In it Prof. A. 

 Tanakadate describes a vertical motion seismometer, in which 

 a mass is so suspended that it is not affected by tilting or 

 by horizontal shocks, and remains in neutral equilibrium 

 for vertical displacements of considerable magnitude. Until 

 this instrument was devised, for large earthquakes at least, 

 vertical spring seismographs, and for that matter horizontal 

 bracket seismographs, have responded to the changes in 

 inclination of their supports, with the result that they have 



