514 



SCIENTIFIC NE\VS. 



[June I, li 



lantern may be described as tank experiments, for they 

 require a special form of glass tank for their performance. 

 This tank can be easily made from three pieces of wood, 

 two pieces of glass, and a short length ot indiarubber 

 tubing. Its construction is as follows : — 



A piece of pine or mahogany, measuring 7 by 4 inches, 

 and five-eighths of an inch in thickness, is cut out with a 

 fret saw to the form shown in fig. 2. This is the 

 foundation of the tank. Two more pieces of wood of 

 the same dimensions are now provided, but they should 

 notbemore than one-eighth of an inch in thickness. Each of 

 these pieces is pierced in its centre with a 3-inch hole, 

 and each piece is then glued and pinned to the founda- 

 tion (fig. 2). The slide will then approach the 

 appearance of fig. 3 ; but it is not yet provided with 

 its glass sides. These glasses, of the flattest and 

 whitest kind, must be cut to the shape of the opening in 

 fig. 2 (as shown at fig. 4), and must just fit that 

 opening without strain. When the glue is dry they can 

 be placed in position, and then separated from one 

 another by the piece of rubber tubing (fig. 5). This 

 last addition completes the tank, the tubing being so 

 pressed between the glasses that it is perfectly water- 

 tight. The contrivance is quickly and cheaply made, 

 and has the advantage of being taken to pieces without 

 difficulty for cleaning. As the tank is chiefly used for 

 chemical experiments the necessity for thorough clean- 

 ing after use will be readily apparent. 



Cambridge. — The following is a list of the distinguished 

 persons upon whom it is proposed to grant honorary 

 degrees.on June 9th. The degree ofLL.D. {honoris causa) 

 will be conferred on : — 



1. His Royal Highness Prince Albert Victor Christian 

 Edward of Wales. 



2. The Marquis of SaHsbury, K.G., D.C.L., F.R.S., 

 Chancellor of the University of Oxford. 



3. The Earl of Selborne, D.C.L., F.R.S. 



4. The Earl of Rosebery, F.R.S. 



5. Lord Randolph Churchill, M.P. 



6. Lord Acton, D.C.L. 



7. The Right Hon. G. J. Goschen, M.A., M.P., Chan- 

 cellor of the Exchequer. 



8. The Right Hon. John Bright, D.C.L., M.P. 



9. The Right Hon. H. C. Raikes, M.A., Trinity, one of 

 the members for the University and Postmaster-General. 



10. The Right Hon. A. J. Balfour, M.A., M.P., Trinity 

 College, Secretary of State for Ireland. 



11. Lieut.-General Sir Archibald Alison, G.C.B. 



12. Professor George Gabriel Stokes, M.A., M.P., of 

 Pembroke College, President of the Royal Society. The 

 honorary degree of Doctor in Science will also be con- 

 ferred upon him. 



The honorary degree of Doctor in Science will also be 

 conferred upon : — 



1. Lord Rayleigh, M.A., F.R.S., Honorary Fellow of 

 Trinity College. 



2. Sir F. A. Abel, C.B., D.C.L., F.R.S., Director of the 

 Chemical Establishment of the War Department. 



3. Professor Arthur Cayley, M.A., F.R.S., of Trinity 

 College. 



4. Professor J. C. Adams, M.A., F.R.S., of Pembroke 

 College, and Honorary Fellow of St. John's College. 



The Chancellor of the University, the Duke of Devon- 

 shire, will preside at the Congregation at which the above 

 degrees will be conferred. 



NEW OBSERVATIONS ON THE 

 " CANALS " OF THE PLANET MARS. 



M. PERROTIN, writing in the Comptes Rendits, states 

 that he has lately had the opportunity of re- 

 examining with a good refracting telescope a portion of 

 the so-called " canals " of Mars, which he studied two 

 years ago. 



They are still in the position where the author saw 

 them in 1886, and they present the same characters. 

 They stand out upon the reddish ground of the con- 

 tinents of the planet as dark straight lines (probably 

 arcs of a great circle), some of them single and the 

 others double — the two component lines being in this 

 case most commonly parallel. They intersect each 

 other at different angles, and seem to establish com- 

 munications between the seas of the two hemispheres, or 

 between the different parts of one and the same hemis- 

 phere. 



Their appearance is, in general, the same as it was 

 in 1886. Some, however, appear fainter, whilst others 

 have in part disappeared. But three important changes 

 have taken place in the meantime, which are the more 

 certain as they have their seat in those regions to which 

 the author's attention was particularly turned m 1886. 



The first of these modifications is the disappearance 

 of a continent which extended then on both sides of the 

 equator through 270" of longitude. It was caWed Lybia 

 in the map drawn up by Schiaparelli. It was triangular 

 in form, being bounded on the south and the west by a 

 sea, and on the north and the east by canals. But this 

 region, distinctly visible two years ago, now exists no 

 longer. The adjacent sea, if sea it be, has totally invaded 

 it. To the reddish-white tint of the continent there has 

 succeeded the blackish or rather deep blue tint oi the 

 seas of Mars. A lake, situated along one of the canals, 

 has likewise disappeared. 



The extent of the region thus completely changed in 

 its aspect is a little larger than the entire surface of 

 France. Whilst encroaching upon this continent the 

 sea has abandoned, to the south, the regions which it 

 formerly covered, and which now present a tint interme- 

 diate between that of the continents and that of the seas. 



This inundation, or whatever else the phenomenon 

 maybe, if we are to rely upon a drawing made in 1882, 

 may be periodic in its character. If so, further observa- 

 tions will detect its law. 



Further to the north of the vanished continent, in about 

 25" latitude, there is a single canal not marked in the 

 chart of Schiaparelli, though this learned astronomer has 

 laid down others which are much fainter. This canal, 

 which extends 20° in length, and has a breadth of i" or 

 I'S", is beyond doubt of recent formation. It is parallel 

 to the equator, and is the prolongation of a double canal, 

 previously existing, which it connects with the sea. 



The third change consists in the very unexpected 

 presence upon the white cap of the North Pole of a 

 canal which seems to form a straight connection, pass- 

 ing right through the Polar ices between two arctic seas. 



It is obviously premature to speculate on the nature 

 and the causes of these phenomena. It might be asked 

 whether the disappearance of a continent is an instance 

 of subsidence, or whether we have to do with cataclysms 

 like those of Adhemar ? M. Faye suggests that the 

 canals may be furrows torn by the tides, which, owing 

 to the proximity of the inferior satellite of Mars, may be 

 very high and powerful. 



