April 3, 1890] 



NATURE 



D^D 



Megacephalon milco. The reviewer corrects, by the way, my 

 calling the Celebean whimbrel Ntiineniiis plueopus, saying that it 

 is probably N. uropvgialis, but these two names are synonymical, 

 cf. for instance, Salvadori, Orn. Pap., ill., 332, 1882, sub N. 

 varicgatiis. As to its nesting on small trees "small brushes" 

 were intended to be implied (see I-egge, "Birds of Ceylon," 

 1880, p. 913). A. B. Meyer. 



Royal Zoological Museum, Dresden, March 22. 



Crystals of Lime. 



It was pointed out to me by Mr. W. J. Pope, of the City 

 and Guilds of London Institute, that a lime cylinder which had 

 been used in the lantern during a lecture had become distinctly 

 crystalline where affected by the oxyhydrogeu flame. 



Examined under the microscope hy polarized light, the crystals 

 are seen to be well-definetl cubes with striated faces. When 

 immersed in water they break up and give rise 10 minute doubly 

 refracting plates of rhombic outline, behaving in this respect like 

 ordinary lime ; the cubic crystals, however, are less rapidly 

 affected by exposure either to air or water than is amorphous 

 lime. 



Lime is commonly stated to be infusible at the temperature of 

 the oxyhydrogen blow-pipe ; and the only crystals previously 

 recorded, so far as I know, are those obtained by Briigelmann, 

 by fusing calcium nilra'e {Annalen der Pliysik und Ckemie, 

 ii. p. 466, iv. p. 277, 1877-78). It seems, therefore, worthy 

 of notice that they are possibly always formed upon the surface 

 of the lime cylinders by the action of the oxyhydrogen flame. 



The crystals resemble in all respects those described by 

 Brilgelmann. The jet used on the present occasion was an 

 ordinary blow-through jet. II. A. Miiius. 



Foreign Substances attached to Crabs. 



I AM glad to see that Mr. Garstang agrees with me in regard- 

 ing the presence of the Ascidians on Hyas as accidental. 



I had no intention of decrying the value of Mr. (iarstang's 

 experiments with Ascidians, but his rule might, perhaps, be 

 limited to those members of the group to which it can be proved 

 to apply. Under natural conditions it apparently fails to apply 

 to /■'. cornigafa and AP. arenosa. As to the latter, Prof. Mclnto h 

 assures me that he has frequently found it in the stomach of the 

 cod and haddock. 



The appreciation of the cod for A. meseinbryanthe/num is, I 

 think, sufficiently proved by the fact that the latter is one of the 

 most successful cod-baits used here. 



Ernest W. L. Holt. 



St. Andrews Marine Laboratory, March 29. 



Wimshurst Machine ani Hertz's Vibrator. 



It may interest those who wish to repeat Hertz's experiments 

 on electro-magnetic radiation to kmw ihat many of these can be 

 done very well by using a small Wimshurst machine in place 

 of the usual induction coil and battery. The vibrator and re- 

 sonator which we used were like those described in Nature 

 (vol. xxxix. p. 548), and the Wimshurst machine had two 

 12-inch plates (giving at most with the jars on a 4-inch spark). 

 The wires from the vibrator, instead of being connected with an 

 induction coil, were connected with the two ouier coatings of the 

 jars of the machine. The machine spark gap and the vibrator 

 spark-gap should be so adjusted that when a spark occurs at 

 the former one also occurs at the latter. With the apparatus 

 described we got good results when the spark-gaps were 38 mm. 

 and 3 mm. respectively. The outer coatings of the jars are only 

 connected together by the wood of the machine, but it is some- 

 times an advantage to put a few inches of damp string between 

 the balls of the vibrator. 



This combination.is obviously a modification, adapted to work 

 a Hertz vibrator, of one of Dr. Lodge's well-known Leyden jar 

 arrangements. 



No doubt many persons have connected the vibrator direct'y 

 with the terminals of the machine, but this arrangement does not 

 work nearly so well. T. A. Garrett. 



W. Lucas. 



THE INSTITUTION OF NAVAL ARCHITECTS. 



HTHE annual meeting of the Institution of Naval Ar- 



-*• chitects was held under the presidency of Lord 



Raven sworth, on Wednesday, Thursday, and Friday of 



last week. There was a fair list of papers on the pro- 

 gramme, although at one time, shortly before the meeting, • 

 it was leared that there would be a sad lack of contribu- 

 tions from meinbers. At the last minute, however, one' 

 or two papers came in, and the list, although perhaps 

 below the average in the importance of the memoirs, 

 was of passable interest. 



The following is a consecutive enumeration of the 

 business that was transacted at the meeting: — 



Wednesday, March 26th : inorning sitting — Annual 

 Report of the Council, an J other routine business ; Address 

 by the President. Paper read and discussed — Notes on 

 the recent naval manteuvres, by Mr. W. H. White, 

 F.R.S., Director of Naval Construction. 



Thursday, March 27th : morning sitting— The Mari- 

 time Conference, by Rear-Admiral P. H. Colomb ; 

 strength of ships, with special reference to distribution of 

 shearing stress over transverse section, by Prof. P. 

 Jenkins ; steatite as a pigment for anti-corrosive paints, 

 by Mr. F. C. Goodall. Evening sitting — ^On the evapora- 

 tive efficiency of boilers, by Mr. C. E. Stromeyer ; on 

 the application of a system of combined sleain and 

 hydraulic machinery to the loading, discharging, and 

 steering of steam-ships, by Mr. A. B. Brown ; the 

 revolving engine applied on ship-board, by Mr. Arthur 



Friday, March 28th : morning sitting — On leak stopping 

 in steel ships, by Captain C. C. Penrose Fitzgerald, R.N. : 

 on the variation of stresses on vessels at sea due to wave 

 motion, by Mr. T. C. Read ; spontaneous combustion in 

 coal ships, by Prof. Vivian Lewes. Evening sitting- 

 Experiments with life-boat models, by Mr. J. Corbett ; on 

 the screw propeller, by Mr. James Howden. 



The annual dinner was held on the evening of 

 Wednesday. 



Out of the above list of a dozen papers there were fewer 

 than usual of scientific interest, and, indeed, in one or 

 two instances they were not either distinguished by prac- 

 tical interest. Mr. White's paper, which formed \\\^ piece 

 de resistance of the meeting, was of military rather than 

 scientific importance, and was chiefly notable from the 

 number of admirals that took part in the discussion ; 

 indeed, the whole naval contingent of the Board of 

 Admiralty was present to hear the paper read. Admiral 

 Colomb's paper on the recent Washington Maritime Con- 

 ference was practically reduced to a consideration of the 

 rule of the road at sea. The general opinion of the 

 authorities assembled appeared to be that the present rule 

 of the road is very well as it stands, with the exception 

 that the " holding-on ship" should not be required, or 

 even allowed, to slacken her speed. This seems in 

 conformity with common sense. If two ships arc- 

 converging towards a point, say at right angles 

 to each other, and one shifts her helm to go under 

 the other's stern, if the second, or holding-on ship, 

 slacken speed, the probability will be that the giving-way 

 ship will crash into the other's broadside or cross her 

 bows ; in the latter case, there is probability that the 

 holding-on ship will give the other her stem. What \=> 

 most wanted when danger of collision arises, is certainty 

 on each vessel as to what the oih.r may be going to do. 

 If the holding-on ship never slacken speed— is not 

 allowed to slacken speed— then the other vessel knows 

 exactly what course to take ; as the law stands, the 

 quartermaster, or officer in charge, is never quite sure 

 until the last minute, e-pecially at night, whether the 

 other ship considers there is danger of collision or not, 

 and, therefore, whether she will slacken or keep to fiill 

 speed. We anticipate the proposed alteration, if put in 

 force, will greatly lessen the list of collisions. 



The memoir contributed by Prof. Jenkins on the 

 strength of ships was decidedly the most important 

 contribution to naval science of this year's meeting. 

 The paper will open up to the majority of those pract.- 



