Dec. 1 8, 1879] 



NATURE 



i53 



ing a correspondence between the / points of the cubic T 

 associated with the quadrilateral T, and the similarly 

 determined u point, and proceeds to examine all the cases 

 in which this correspondence is uniform, i.e., when to a 

 point of each curve corresponds a single point of the other 

 curve. He then shows that all other cases may be reduced 

 to this case of uniform correspondence. His conclusion, 

 after a discussion of these equations of condition, is that 

 there are no other solutions besides those deduced from the 

 uniform correspondence cases. He establishes coinci- 

 dences with most of the cases discussed in Mr. Kempe's 

 paper, and arrives at one new case, viz., when Mr. 

 Kempe's triangles reduce to straight lines coinciding with 

 the sides respectively of T and U. 



Our object has been to draw attention to what we look 

 upon as a valuable pendant to the last-named gentle- 

 man's Researches in Linkworks. 

 Lecture Notes on Physics. By C. Bird, B.A., F.R.A.S- 



(London: Simpkin, Marshall, and Co., 1S80.) 

 The author says in his preface that the book "may be 

 supposed to represent the notes, somewhat expanded, 

 which the teacher would desire the class to take down 

 and learn." If so, the " notes " before us would certainly 

 merit a good deal of attention from the teacher's red-ink 

 pen. Of its 178 pages, 68 are taken up with examination 

 papers of the Science and Art Department. The various 

 branches of physics are very unequally treated. Occa- 

 sional blunders are frequent. Thus on p. 27 we are told 

 that " Writing m for the refractive index, the critical 



angle for any medium is — ." On p. 2 Laplace's correc- 

 tion of the velocity of sound for the adiabatic conditions 

 is stated to be the ratio of the two specific heats of air, 

 when it should be the square root of that ratio. On the 

 very next page we are told that the amplitude of a sound- 

 wave varies inversely as the square of the distance from 

 the source, and that therefore the intensity falls off in the 

 same ratio ; whereas in fact the intensity is proportional 

 to the 'square of the amplitude. Under the heading 

 "Electrometers" we observe that the only instruments 

 named are the quadrant pith-ball electroscope, the torsion 

 balance (which is not even described), and the unit-jar ! 

 But one could hardly expect accuracy of an author who 

 allows himself to talk about "force" being " converted 

 into heat." 

 Diagrams of Zoology. Sheet I. and II., with handbooks 



thereto. By Dr. Andrew Wilson. (Edinburgh and 



London : W. and A. K. Johnston.) 

 THESE sheets are meant to serve as important adjuncts 

 in the way of illustrating a series of lectures on the 

 classes to be met with in the animal kingdom. They 

 have been drawn and coloured under the direct superin- 

 tendence of Dr. A. Wilson, and are accompanied by a 

 handbook to each sheet which contains full descriptions 

 of each figure. They will no doubt be found most useful 

 for the purposes of science classes in our public schools, 

 and in them illustrations of recently described forms will 

 be found. For example, under the kingdom of the 

 protozoa, we find no less than five figures representing that 

 low form of animal life called by Hseckel Protomyxa 

 aurantiacea, one of the Monera. 



LETTERS TO THE EDITOR 



\ The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspotid with the writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting and novel facts.] 

 The Exploration of Socotra 

 Would you allow me, on behalf of the Committee of the 

 British Association for the Advancement of Science for the Ex- 



ploration of Socotra, to state in your columns that we are 

 anxious to find a competent naturalist to proceed to Socotra early 

 next year, the gentleman whose services we had hoped to secure 

 being unfortunately unable to undertake the task. The expedi- 

 ti n w ill be but a short one, as it would be useless to remain in 

 the island after April. 



It would be desirable that the explorer should have some 

 acquaintance with Arabic and some local knowledge of the sur- 

 rounding districts. P. L. Sclater 



1 1, Hanover Square, W. 



Monkeys in the West Indies 



In reply to the inquiries of Mr. Watt (Nature, vol. xxi. p. 

 132), I send you the following extract from the Proceedings of 

 this Society for February 13, 1866. 



"Mr. Sclater called the attention of the meeting to three 

 monkeys recently received from the Island of St. Kitts, West 

 Indies. Mr. Edward Greey, Fellow of the Society, having 

 reported the existence of monkeys in a wild state in considerable 

 numbers upon this island, had been urged by Mr. .Sclater to 

 attempt to obtain some specimens, in order that it might be 

 ascertained to what species they were referable, as it had always 

 been believed that there were no native Quadrumana in the 

 Lesser Antilles. Through the assistance of Mr. John Garden, ot 

 St. Kitts, Mr. Greey had succeeded in obtaining a specimen of 

 this monkey, and two others from the same island had at 

 the same time been presented to the Society by Mr. H. B. 

 Cameron, Superintendent of the R.W.I.M.S.P. Company, at 

 St. Thomas's. The animals were undoubtedly referable to the 

 common green monkey (Cercopithecus calhtrichus, Geoffr.) of 

 Western Africa, and must have been introduced years ago, as 

 they were stated to be now very abundant in the woods of St. 

 Kitts, and to cause great damage to the sugar-plantations." 



As regards Trinidad, where true American monkeys (Cebid<c) 

 are certainly found, it should be recollected that, zoologically 

 speaking, Trinidad is not one of the Antilles, but a little bit of 

 Venezuela, broken off at no very remote period. 



Trof. Mivart and Mr. Bates are, therefore, correct in saying 

 there are no indigenous monkeys in the Antilles. 



P. L. Sclater 



Zoological Society of London, 1 1, Hanover Square, W. 



Is Mount Unzen a Volcano? 



In a recent visit to the Simabara Peninsula, about twenty miles 

 east of Nagasaki as the crow flies, an opportunity was afforded 

 me of ascending " Unzen," a mountain which rises about 

 4,700 feet above the sea (by aneroid). If tradition is to be 

 believed " Unzen" is an active volcano, the subterranean fires 

 of which have been slumbering since the close of la-t century, 

 when a disastrous earthquake, accompanied by a volcanic erup- 

 tion destroyed 53,000 of the inhabitants of the district. But I 

 failed to find any trace of a recent volcano, which, w herever it 

 may be, is certainly not situated in the higher peaks of the 

 mountain, where popular belief has located it. From the sea- 

 level up to the highest summit a porphyry is the ever-prevadmg 

 rock which varies somewhat in different parts of the peninsula. 

 True' it is that from many points of view Unzen has somewhat 

 the form of a truncated cone, but there the resemblance ends. 



There are, however, three hot sulphur springs, which may help 

 to explain the popular error on the subject. One of them is 

 situated in the fishing village of Wobama, at the foot of the 

 mountain, and close to the water ; a strong odour of sulphuretted 

 hydrogen scents the air, and the thermometer placed in the 

 water rose to 112 F. Rather more than 2,000 feet above the 

 sea are the hot springs of Kojeego and Unzen. In the former 

 place the water bubbles up into a pool some ten or fifteen yards 

 across, with a temperature of 182 , while at Unzen the hot 

 springs are on a far more extensive scale, numerous springs 

 bubbling away furiously over an area of several acres, winch is 

 completely destitute of vegetation. The ground is often so hot 

 that with a thick pair of boots one cannot stand long on the 

 same spot. The thermometer rose as high as 202% which would 

 be only about 6° below the boiling-point of water at that eleva- 

 tion, and a dense cloud of white smoke ascended into the air 

 which was strongly impregnated with the same sulphureous odour 

 The chemical and thermal influences of these hot sulphur spring, 

 have produced a singular effect on the porphyry of the immediate 



