342 



sciujsrcu. 



(Vol. IX., ^'o. 218 



Though moderately well sheltered, the little bay 

 at Na-wi-ti is stated in the Vancouver pilot to be un- 

 STiited for an anchorage by reason of its rocky bot- 

 tom. It is nevertheless the first place on the north 

 shore in which a seaman would naturally seek for an 

 anchorage after rounding Cape Scott in the absence 

 of a chart, and was, besides, adapted to the purpose 

 of the traders as being the site of a large village. 

 The mention by Cox of a bar over which a strong 

 tide runs, again agrees with the fact of the existence 

 of the notable 'Nahwitti Bar' of the charts, of 

 which the writer had a somewhat perilous experience 

 ten years ago, while bars are not found at the en- 

 trances of Nootka or Clayoquot sounds. 



When at Na-wi-ti in 1885, I learned from the In- 

 dians that some disastrous event had happened at 

 this place, but could not learn its precise nature. 

 Dr. Franz Boas informs me that he also was unable 

 to gather any thing definite on the subject from the 

 natives. It is probable, however, that the shelling 



Mires 



of this village by a gunboat, which occurred about 

 forty years after the loss of the Tonquin, may have 

 since become confounded with that event, if it reallj'^ 

 happened at this place. 



The point at which the Tonquin is supposed to 

 have been destroyed is indicated by the asterisk on 

 the accompanying plan, which is based on Admiralty 

 chart No. 582. George M. Dawson. 



Geol. surv. Can., March 30. 



A sensitive vT^ind-vane. 



The liquid damper suggested by ' T. C. M.' in 

 Science, No. 217, certainly furnishes a complete and 

 satisfactory solution of the wind-vane problem. This 

 device is a customary method of checking oscilla- 

 tions, and its application to the wind-vane was made 

 about ten years ago by Mr. J. W. Osborne, who con- 

 structed and used such an apparatus (Amei\ assoc. 

 report, 1878). His definition of an ideal vane agrees 

 entirely with the conditions laid down by Professor 

 Mendenhall, and is worth quoting : "A perfect wind- 

 vane should instantly respond to the slightest change 

 in the direction of the wind, and should remain 

 stationary when it has made the necessary angular 

 movement." 



A single, biit perhaps not unimportant, exception 

 may be taken to Professor Mendenhall's solution, — 

 "to use a small and extremely light vane." Light- 

 ness is, of course, a desideratuna in order to reduce 

 friction, but length is also requisite in order to give 

 sufficient gyratory force for very light winds. The 

 vane may be extremely light, and yet not small. Mr. 

 Osborne's vane, designed to realize his definition, was 

 seven feet long, and weighed only three ounces. 

 Sensitiveness is increased, 1°, by increasing the 

 moment of rotation ; 2", by diminishing the friction. 

 An addition to the length of a vane, if it is of light 

 material and moimted on friction-rollers, may add 

 more to the sensitiveness by increasing the moment 

 of rotation than it will subtract by increasing the 

 friction. G. E. Cuetis. 



Washington, D.C., April 4. 



The difficulties which have been discussed in the 

 last few numbers of Science in regard to a sensitive 

 wind-vane are avoided at Blue Hill observatory by 

 having the wind-vane self-recording. 



The recording is by the Draper method ; viz. , a 

 cylinder is attached to the spindle of the vane, and a 

 stationary pencil (except that it is slowly dropped 

 by clock-work) records the oscillations of the wind 

 on the cylinder. The vane is thin metal, has a di- 

 vided tail, and is sensitive to the lightest wind. In 

 order to determine the direction of the lightest or 

 most violent wind, a line is drawn through the cen- 

 tre of the oscillations recorded on the cylinder. It is 

 not uncommon for scud-clouds to drive by almost 

 touching the top of Blue Hill ; and, by means of a 

 mirror devised for measuring cloud-movements, 

 their motion can be determined within one or two 

 degrees of arc. I have made a number of such 

 measurements, and find that they correspond almost 

 exactly with the centre of the wind-oscillations on 

 the cylinder, determined in degrees of arc. 



This method of recording the wind-direction is 

 simple, accurate, and easily managed, and I do not 

 think it would cost very much more than the 

 method Professor Mendenhall suggests of fitting up 

 the vane. Hence I hope, if improvements in wind- 

 vanes are attempted by the signal service, they will 

 turn their attention to the very desirable method of 

 continuous registration. H. Helm Clayton. 



Blue Hill meteor, observ., April 3. 



Physiology of plants. 



I notice that in a review in Nature of the 26th of 

 August, 1886 (p. 381), of Dr. Vines's 'Lectures on 

 the physiology of plants,' it is stated that the view 

 that " the cell-wall is produced by the actual con- 

 version of a layer of protoplasm," and that "the 

 starch which is formed in chlorophyll corpuscles 

 under the influence of light is also the product of 

 such a dissociation of protoplasm," is "the most 

 striking novelty which will be found by English read- 

 ers" in Dr. Vines's book, " and, though propounded 

 some years ago in Germany, has now, we believe, 

 appeared for the first time in an English text-book." 



In reference to this, will you kindly allow me to 

 point out that the above view was propounded by 

 myself, and will be found fully set forth, along with 

 an explanation of the chemical reactions involved, on 

 pp. 218-223 of my book, ' Light the dominant force 

 of the universe ' (London, Sampson Low & Co., 

 1882). W. Sedgwick. 



Calcutta, Feb. 15. 



