54 



NATURE 



[March io, 192 i 



F; Santschi on South American ants, by G. Bonarelli 

 on the human mandibles of Banolas, and by J. 

 Brethes on the South American bees of the genus 

 Xylocopa, Latr. It may be added that two out of 

 three of the above papers are written in French. 



The presidential address delivered by Comdr. J. J. 

 Walker before the Entomological Society on January 19 

 dealt with " Some Aspects of Insect Life in New- 

 Zealand." It contains interesting information useful 

 to the student of geographical distribution. As the 

 author points out, the noble forests of the two islands 

 are now little more than memories, and more than 

 350 species of introduced trees, shrubs, and weeds are 

 ousting- what is left of the indigenous flora. It is 

 also a matter of certainty that the exceptional fauna 

 of New Zealand is to a great extent doomed to extinc- 

 tion, and no effort should be lost to acquire as much 

 information as possible concerning the animal life 

 before the latter also is a thing of the past. Comdr. 

 Walker comments on the very general opinion that 

 New Zealand possesses the most limited insect fauna 

 of any land of the same extent. He attributes this 

 belief to the nocturnal or unobtrusive habits of many 

 species, a large number being either inactive or 

 retiring; many are cryptically coloured and hard to 

 detect, and others very local. About 4000 species of 

 Coleoptera are known, but the Cetoniadae and Cas- 

 sididae are absent. More than 1000 species of 

 I^pidoptera inhabit New Zealand, and all except 

 about 70 are indigenous. The butterflies, however, 

 ar^ very poorly represented, only 15 species being 

 recorded. Diptera are abundant, but Hemiptera and 

 Hymenoptera are comparatively few. 



During the meeting of the Science Masters' Asso- 

 ciation at Oxford on January 5 and 6, some interest- 

 ing demonstrations (with exhibits) were given by Mr. 

 T. V. Barker in the mineralogical department of the 

 University Museum on the subject of the study of 

 crystals in schools, and a pamphlet of " Practical 

 Suggestions " has been drawn up embodying the main 

 facts dealt with. It is designed to amplify a 

 previous pamphlet which was noticed in Nature 

 of September 2 last, p. 28. The preparation of solu- 

 tions for crystallisation, instructions for the screen- 

 projection of the crystals grown, the nature of 

 crystals, isomorphism, polymorphism, and crystal 

 structure as revealed by simple measurements were 

 a few of the subjects dealt with in an attractive 

 manner. As an example of the style adopted, a few 

 lines from the reference to the isomorphism of the 

 two acid phosphates of potassium and ammonium 

 may be quoted: — "When the pupil has observed and 

 measured both substances [under the microscope], he 

 will agree with Mitscherlich that the two forms are 

 isomorphous in the literal sense ; and if some two 

 years later he came to measure them with the reflect- 

 ing goniometer he would, like Mitscherlich, revise his 

 opinion and conclude that they are closely similar, but 

 not identical, in angles." 



The variations of "mean sea-level" on the Flemish 



coast have been analysed by Dr. Bruno Schulz and 



the results published by the Deutsche Seewarte {AerO' 



logische und Hydrographische Beobachtungen den 



NO. 2680, VOL. 107] 



Deutschen Marine-Stationen wdhrend der Kriegszeit, 

 1914-18, Heft i). Owing to war conditions full 

 weather information was lacking, and the paper is 

 chiefly concerned with long-period oscillations and 

 with the correlation between non-periodic variations 

 and local wind. Formulae are given as representing 

 these effects. It is interesting to note that it was 

 impossible to use as data the difference between 

 observed and predicted tides owing to the obvious 

 errors of the latter, and daily means of hourly heights 

 were used in conjunction with monthly and annual 

 means. The wind effects are sorted according to 

 direction and strength. The best results are found 

 to be given by comparing the tidal height at a given 

 time with the wind about three hours earlier. After 

 allowing for wind there is a residual effect attributed 

 to air-pressure ; the ratio between simultaneous 

 changes in sea-level and in barometer is found to 

 have an average value of 10-3, the statical value 

 being 13-4. Apparently the long-period oscillations, 

 win-i effects, and air-pressure effects are treated a« 

 being quite independent. There is great need for 

 further work on these important problems, especially 

 in this country. 



In his presidential address to the Optical Society on 

 February 10 Mr. Robert S. Whipple emphasised the 

 influence of the design of scientific instruments on their 

 accuracy, sensitivity, and cost of production. An 

 instrument may be rendered ineffective by bad design 

 of the moving parts, by unsuitability of the materials 

 employed, or by bad workmanship. The selection of 

 the materials, however, is part of the design, and 

 good design will often minimise the effect of bad 

 workmanship, though the converse is not true. A 

 consideration of the fundamental principles of instru- 

 ment construction shows the advantages of the geo- 

 metric form of design. By geometric design internal 

 strain in the parts of an instrument can be greatly 

 reduced and backlash between the different parts 

 eliminated. Geometric design may also simplify con- 

 struction and thus materially reduce the cost of manu- 

 facture. The new applications of research to in- 

 dustry in many cases involve the new application of 

 an old instrument. Thus the research instrument of 

 to-day becomes the tool of to-morrow. In designing 

 an instrument the manufacturer should, therefore, 

 always have in mind the possibility of quantity pro- 

 duction, so that the instrument can be readily 

 developed from its laboratory form to one suitable 

 for the workshop and capable of being manufactured 

 on a large scale. Cheap production is thus rendered 

 possible, and this is an important factor, especially 

 in view of the keen competition which the scientific 

 instrument industry of this country has now to meet. 



Part ii. of the Transactions of the Institution of 

 Engineers and Shipbuilders in Scotland contains a 

 paper by Prof. A. L. Mellanby and W. Kerr on 

 pressure-flow experiments on steam nozzles. This 

 paper is the second of a series on the same subject, 

 the preceding paper having been presented to the 

 British Association in August last. The measure- 

 ments of pressure were carried out by means of a 

 search-tube, which, when moved along the jet, gave 



