December 19, 1895] 



NATURE 



161 



chapter to the work on agriculture and forestry, which was 

 published by the Russian Government at the time of the 

 Chicago Exhibition, and was translated into English by Mr. J. 

 M. Crawford, the Consul-General at St. Petersburg. 



Acting upon the report of the Departmental Committee on 

 the Screening of Side Lights of Ships, the Board of Trade 

 have issued the following instructions to their surveyors through- 

 out the country : — The Committee appointed by the Board of 

 Trade under minuie of March i8, 1895, to consider the question 

 of the screening of side lights have reported, inter alia: 

 1 1) That the Order in Council of January 30, 1893, ^^ cancelled. 

 (2) That in the case of oil lamps the forward edge of the screen, 

 or chock on it, should be in a line parallel to the keel with the 

 inside edge of the wick. (3) That in the case of electric lights 

 there should be a similar screening in regard to the inside edge 

 of the filament. (4) That the breadth of the wick of oil lamps, 

 and of the filaments in the case of the electric light, should be 

 not more than two inches, nor less than one inch, measured at 

 right angles to the fore and aft line of the ship. The Board 

 having decided to adopt the above recommendations, the sur- 

 veyors are informed that the instructions as to the screening of 

 side lights contained in the present issue of " Instructions as to 

 the Survey of Passenger Accommodation, Master's and Crew 

 Spaces," *' Lights and Fog-signals,"' so far as they have either 

 direct or indirect reference to the lights being screened to an 

 angle of convergence of 4° from the outside edge of the wick, 

 are no longer to be put in force, but instead thereof the surveyors 

 are to carry out the directions as to screening contained in above 

 paragraphs, numbered 2, 3, and 4. 



The better protection of wild birds was the object of a deputa- 

 tion that waited upon the Home jSecretarj' on Tuesday. The 

 'leputation consisted of members of the eight Councils having an 



rea within the Metropolitan Police district. Mr. Montagu 

 ">harpe said they desired to urge (i) that the close time under 

 -section 8 of the Act of 1880 should be extended ; (2) that 



hirteen new species of birds, in addition to those mentioned in 

 Section 3 of the Act of 1894, should be scheduled ; and (3) that 

 the eggs of forty six species of birds should be scheduled for pro- 

 tection under Section 2 of the Act of 1894. It was desired that 

 the close time for wild birds should be extended to the period 

 between February i and August [31. The birds which it was 

 sought to add to the list were the wryneck (cuckoo's mate, or 

 snake-bird), swallow, martin (2), swift, bearded tit (reedling and 

 reed pheas^nt^ kestrel, merlin, hobby, buzzard, honey buzzard, 

 osprey, magpie, and shrike. These birds should be protected 

 not only for their beauty, but for their usefulness in destroying 

 noxious insects, mollusca, and rodents, which were particularly 

 destructive in suburban gardens. The Home Secretary expressed 

 agreement with the proposals of the deputation, and said he 

 would comply with their desire with regard to the scheduling of 

 birds and their eggs. 



An improvement on the simple pendulum for purposes of 

 measurement is described by G. Guglielmo in the Atti dei 

 Lincei. The simple pendulum oscillates about its point of 

 suspension in all directions. The compound pendulum rests on 

 a knife-edge, or essentially on two points some distance apart, 

 and therefore oscillates always in the same plane. A bob sus. 

 pended by two threads will do the same, and will have the 

 additional advantage of simplicity. But for some purposes it is 

 highly desirable to have a body oscillating in the same plane, 

 and parallel to itself. Sgr. Guglielmo has accomplished this by 

 taking two such bifilar pendulums and joining them by a 

 horizontal rod placed in their plane of vibration. This contriv- 

 ance can be used for a variety of purposes. An electrometer is 

 described in which the rod is replaced by a small cylinder 

 i loving inside another, and displaced by any difference of 

 NO. 1364, VOL. 53] 



potential between the two. A very useful application of it is 

 the anemometer designed on this plan. A vertical disc is fixed on 

 one end of the rod, and exposed directly to the wind. Wild's ane- 

 mometer, which consists of a simple plate, the inclination of which 

 alter* with ths strength of the wind, does not give the horizontal 

 velocity of the wind in a simple manner. The new anemometer 

 always exposes a vertical disc to the wind, and the force is 

 directly given by the deflection of the suspending wires. It 

 should be mentioned that the suspending wires are of iron, 

 joined to the rod and to the supports by short lengths of silk 

 thread to ensure flexibility. Many interesting investigations 

 may be carried out with this apparatus : the influence of the 

 inclination of the disc may be studied, and the indications of 

 Robinson's revolving anemometer may be verified. Oscillations 

 are effectively damped by a wire attached to the rod with a disc 

 attached to its lower end and immersed in water. 



With the scientific intelligence in the December number of 

 the American Journal of Science, we find the following note on 

 underground temperatures at great depths, received by the 

 editors from Prof A. Agassiz :— " For several years past I have, 

 with the assistance . of our engineer, Mr. Preston C. F. West, 

 been making rock temperature observations as we increased the 

 depth at which the mining operations of the Calumet and Hecla 

 Mining Company were carried on. We have now attained at 

 our deepest point a vertical depth of 4712 feet, and have taken 

 temperatures of the rock at 105 feet, at the depth of the level 

 of Lake Superior, 655 feet, at that of the level of the sea, 1257 

 feet, at that of the deepest part of Lake Superior, 1663 feet, 

 and at four additional stations, each respectively 550, 550, 561, 

 and 1256 feet below the preceding one, the deepest point at 

 which temperatures have been taken being 4580 feet. We pro- 

 pose, when we have reached our final depth, 4900 feet, to take 

 an additional rock temperature, and to then publish in full the 

 details of our observations. In the meantime it may be interest- 

 ing to give the results as they stand. The highest rock tempera- 

 ture obtained at the depth of 4580 feet was only 79° F. ; the 

 rock temperature at the depth of 105 feet was 59' F. Taking 

 that as the depth unaffected by local temperature variations, 

 we have a column of 4475 feet of rock with a difierence of 

 temperature of 20° F., or an average increase of 1° F. for 2237 

 feet. This is very different from any recorded observations ; 

 Lord Kelvin, if I am not mistaken, giving as the increase 

 for i" F., fifty-one feet, while the observations based on the 

 temperature observations of the St. Gothard tunnel gave an 

 increase of i" ¥. for sixty feet.. The calculations based upon 

 the latter observations gave an approximate thickness of the 

 crust of the earth, in one case of about twenty miles, the other 

 of twenty six. Taking our observations, the crust would be 

 over eighty miles, and the thickness of the crust at the critical 

 temperature of water would be over thirty-one miles, instead of 

 about seven, and 85 miles as by the other and older ratios. 

 With the ratio observed here, the temperature at a depth of 

 nineteen miles would only be about 470°, a very diflTerent 

 temperature from that obtained by the older ratios of over 2000" 

 F. The holes in which we placed slow registering Negretti 

 and Zanibra thermometers were drilled, slightly inclined upward, 

 to a depth of 10 feet from the face of the rock, and plugged with 

 wood and clay. In these holes the thermometers were left from 

 one to three months. The average annual temperature of the 

 air is 48" F., the temperature of the air in the bottom of the 

 shaft was 72° F." 



The first part of a cheap edition of "Science for All" has 

 just been published by Messrs. Cassell and Co. So far as we 

 can see, few revisions have been made ; hence the work in no- 

 wise represents the state of scientific knowledge at the present 

 time. 



