March 17, 1892] 



NATURE 



461 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of 'Nature. 

 No notice is taken of anonymous communications, "l 



Carpenter on Eozoon. 



The scientific world is deeply indebted to Dr. Dallinger for 

 his excellent new edition of Carpenter's invaluable work on the 

 microscope, and among other things for his retaining unchanged 

 the description of Eozoon canadeuse, as a monument of an im- 

 portant research up to a certain date. 



Dr. Carpenter devoted much time to the study of Eozoon, and 

 brought to bear on it his great experience of foraminiferal forms, 

 and his wonderful powers of manipulating and unravelling diffi- 

 cult structures. After having spent years in studying microscopic 

 slices of Eozoon and the limestones in which it occurs, I have 

 ever felt new astonishment when I saw the manner in which, by 

 various processes of slicing and etching, and by dexterous 

 management of light, he could bring out the structure of 

 specimens often very imperfect. Not long before Dr. Carpenter's 

 death I had an opportunity to appreciate this in spending a few 

 days with him in studying his more recently acquired specimens, 

 some of them from my own collections, and discussing the 

 new points which they exhibited, and which unhappily he did 

 not live to publish. Some of these new facts, in so far as they 

 related to specimens in our cabinet here, have since that time 

 been noticed in my resume of the question in the Memoirs of 

 the Peter Redpath Museum, 1888 ; but I hope my friend Prof. 

 Rupert Jones may yet be able to complete Dr. Carpenter's 

 work. 



Those who know Dr. Carpenter's powers of investigation will 

 not be surprised that later observers, without his previous pre- 

 paration and rare insight, and often with only few and imperfect 

 specimens, should have failed to appreciate his results. One is 

 rather surprised that some of them have ventured to state with 

 bO great confidence their own negative conclusions in a matter of 

 so much difficulty, and requiring so much knowledge of organic 

 structures in various states of mineralization. For myself, after 

 working for fifty years at the microscopic examination of fossils 

 and organic rocks, I feel more strongly than ever the uncer- 

 tainties and liabilities to error which beset such inquiries. 



As an illustration in the case of Eozoon : since the publication 

 of my memoir of 1888, which I had intended to be final and 

 exhaustive as to the main points, and in so far as I am con- 

 cerned, I have had occasion to have prepared and to examine 

 about 200 slices of Eozoon from new material : and while most 

 of these have either failed to show the minute structures or have 

 presented nothing new, a few have exhibited certain parts in 

 altogether unexpected perfection, and have shown a prevalence 

 of injection of the canal system by dolomite not previously 

 suspected. Since that publication also, the discoveries of 

 Mr. Matthew in the Laurentian of New Brunswick, and the 

 further study of the singular Cambrian forms of the type of 

 Cryptozoum, have opened up new fields of inquiry. 



I think it proper to state, in reference to Dr. Dallinger's foot- 

 note on the recent paper of Mr. Gregory, that it must not be 

 inferred from it that Mr. Gregoiy had access to my specimens 

 from Madoc and Tudor, though he no doubt had excellent 

 material from the collections of the Canadian Geological Survey. 

 It might also be inferred from this note that I have regarded the 

 .Madoc and Tudor specimens as " Lower Laurentian." The 

 fact is that I was originally induced in 1865, by the belief of 

 Sir W. E. Logan at that time that these rocks were representa- 

 tives in a less altered state of the middle part of the Laurentian, 

 to spend some time at Madoc and its vicinity in searching for 

 fossils, but discovered only worm-burrows, spicules, and frag- 

 ments of Eozoon, which were noticed in the Journals of the 

 Geological Society for 1866. (The more complete specimen 

 from Tudor was found by Vennor in 1866.) On that occasion I 

 ^atisfied myself fully that the beds are much older than the 

 Cambro-Silurian strata resting on them unconformaily ; but I 

 felt disposed to regard them as more probably of the age of 

 some parts of the Huronian of Georgian Bay, which I had ex- 

 plored with a similar purpose under Logan's guidance in 1856. 

 As my work was not official, and was palseontological rather 

 than stratigraphical, it did not seem proper to express any dissent 

 from what were at the time the probable conclusions of strati- 



NO. I 168, VOL. 45] 



graphical work ; but I was quite prepared to assent to the new 

 views afterwards adopted. 



In conclusion, the new material bearing on Eozoon is ac- 

 cumulating so rapidly that I cannot hope to he able to master it 

 in detail, but shall be glad to aid others who may have more 

 time ; but I hope to be able, in a work now in preparation, at 

 least to present the facts up to date in a popular form. 



J. William Dawson. 



McGill College, Montreal, February 3. 



The Samoan Hurricane. 



Replying to the communication in Nature of December 17, 

 1891 (p. 161), signed " H. F. B.," relative to my preliminary 

 report on the Samoan hurricane of March 1889 (published in 

 the Proceedings, U.S. Naval Institute, vol. xvii.. No. 2, and in 

 the American Meteorological Journal, July 1891), I would 

 submit the following statement. 



First of all, I wish to acknowledge Mr. Blanford's apprecia- 

 tion of the difficulties involved in the consideration of the subject, 

 owing to the meagreness of the data ; and at the same time to 

 express my own appreciation of the fact that he himself has not 

 had access even to such data as we have succeeded in collecting, 

 but only to my necessarily brief discussion thereof, and the con- 

 clusions that 1 have drawn therefrom. 



Mr. Blanford's explanation, as I understand it, is as follows : 

 the vortex of the hurricane formed north or north-east (on the 

 equatorial side) of Apia on the afternoon of the 15th, within a 

 "region of disturbance " that had already caused stormy weather 

 throughout the Samoan Islands and a decided barometric de- 

 pression at Apia. The first effect of this formation was (by 

 adding slightly to the normal evening rise of the barometer) to 

 cause a decided rise of pressure, which, however, decreased 

 again as the vortex slowly approached the harbour, thus causing 

 the second minimum (the afternoon of the l6th), the duration of 

 the storm being explained by the usual slow motion of the 

 newly formed hurricane. 



To the above explanation it is necessary to make a correction, 

 I think, owing to the fact that the shifts of wind at the time 

 of and immediately after the first minimum show that the centre 

 of the disturbance then passed to the westward of Apia, and as 

 the wind thereafter remained from north to north-east, the centre 

 (or vortex) evidently remained to the southward and westward. 

 This fact, however, merely introduces a change in the position 

 where the new vortex formed, according to the theory under 

 discussion. 



Revising Mr. Blanford's explanation, then, in the light of this 

 correction, it appears that the track of the depression is about as 

 I have drawn it, but that a vortex formed slightly to the south- 

 ward and ivestiuard of Apia, thus causing a slight rise of 

 pressure at first, succeeded by a second fall, and the slow 

 motion of this newly formed vortex caused the duration of the 

 northerly gale. 



Now, I must here take exception to one of Mr. Blanford's 

 statements, which is as follows (referring to the theories given 

 in my paper): "None of these explanations seem to take 

 account of the circumstances that attend the formation of tropical 

 cyclones, which, as we have elsewhere pointed out, differ in 

 many respects from the storms of the temperate zone." A 

 reference to my paper will show, I think, that I took into con- 

 sideration the special peculiarity to which Mr. Blanford calls 

 attention, and went so far as to insert a plate in order to 

 illustrate two types of storms — namely, (i) the characteristic 

 tropical hurricane type (where there is a decided vortex, or 

 "centre of aspiration") ; and (2) the type where there is a 

 comparatively wide central region surrounded by an annular 

 space where there are steep barometric gradients and cor- 

 respondingly high wind velocities, but without any decided 

 vortex, properly so called. I said also that "it will be seen 

 that the indications are that the Samoan hurricane (on the isth 

 and i6ih, at least) was of the second type, although during 

 the 17th and i8th it doubtless became more like the first." In 

 a word, I said (both explicitly and by means of the varying 

 strength of the track drawn on the chart) that the depression 

 passed Apia on the afternoon of the 15th, recurved (increasing in 

 intensity and delaying whilst recurving, each of which is to be 

 expected), and then moved off to the southward and eastward. 

 I do not intend to convey the impression that I made any 

 definite statement as to just when or where the vortex formed, 

 nor am I wholly prepared to hazard such a statement even at 



