Feb. 27, 1879] 



NATURE 



401 



at right angles to its first position, the maximum velocity came 

 nearer it, and had the cannon been pointed towards the mem- 

 branes, the retardation would probably have become an accelera- 

 tion. — Dr. Ihlseng has measured the velocity of sound in wood, 

 both by Kundt's method and the graphic method, in which latter 

 a blackened glass plate was drawn rapidly in a horizontal direc- 

 tion (across the direction of the rod's length), by a falling weight, 

 and a pen attached to the rod wrote its vibration on the plate, 

 which also registered those of a tuning-fork. This method was 

 foimd one of considerable accuracy. Its results were slightly 

 below those by Kundt's method, and (when the plate was moved 

 in a dififerent direction) it demonstrated the existence of trans- 

 verse along with longitudinal, and gave their ratios. — Mr. Pum- 

 pelly writes on the relation of secular rock disintegration to loess, 

 glacial drift, and rock basins ; Mr. Fontaine continues his notes 

 on the mesozoic strata of Virginia ; and Mr. Hawes describes a 

 group of dissimilar eruptive rocks in Compton, New Hampshire. 

 — In a method of determining dip, devised by Mr. Hodges, a 

 compound bar is used consisting of two joined at right angles at 

 a point near their ends ; when placed so that the two branches 

 make equal angles with the line of dip, the two joined poles 

 neutralise each other, and any needle suspended near that point 

 is unaffected. A slight turning of the compound bar renders the 

 field round the needle a north or a south, and the needle moves 

 correspondingly. — Some notices of recent American earthquakes 

 are furnished by Prof. Rockwood, Jun. 



journal de Physique, January. — This number opens with M. 

 Toubert's researches on the rotatory power of quartz and its 

 variations with the temperature ; they prove that quartz consti- 

 tutes a thermometer of extreme sensibility. — A new and simple 

 regulator of velocity, for electric motors especially, described by 

 M. Deprez, rests on the principle of centrifugal force acting on 

 one end (loaded) of a flexible metallic strip, and (with a certain 

 intensity) breaking contact of an adjusting screw at that end 

 with a metallic piece, and so stopping a current which actuates 

 the motor. — M. Witz studies the thermal effects of the walls of 

 an inclosure on the gases it contains. — M. Pellat describes an 

 apparatus for effecting the synthesis of compound colours, the 

 very colours of the spectrum being taken in the desired propor- 

 tions and mixed completely ; and M. Schwedoff one for study- 

 ing the vibratory movements of cords, the cord being 'set in 

 motion by means of an electric trembler at one end. 



The Sitzungsberichte der naturwissenscJiaftlichen Gesellschaft 

 Isis in Dresden (1878, part I, January to July) contain the 

 following papers of interest : — On Heligoland and Nordemey 

 from a geological point of view, by C. D. Carstens. — On 

 the tertiary flora of the Klein Purberg near Czemov\'itz, by 

 Herr Engelhardt. — On amber, by Dr. O. Schneider. — On the 

 saltpetre and the guano from the Atakama Desert, by Herr 

 Weis. — On fossil man, by Herr Engelhardt. — On some pre- 

 historic remains discovered on the Hradischt in Bohemia, by 

 W. Osborne. — On palm leaves, by Herr von Biedermann.-— On 

 the largest elm tree of Germany, by C. F. Seidel. The tree in 

 question stands in the village of Schimsheim near the railway 

 station of Armsheim in Rhenish Hessen, and measures 30 metres 

 in height, its trunk 15 '07 metres in circumference, while its age 

 is estimated at close upon 600 years. — On the colour which a 

 gas flame assimies in the vapour generated by a mixture of per- 

 manganate of potash and sulphuric acid, by Carl Bley. — On the 

 formation of crude coralline and of resorcine-oxaleine, by Dr. 

 Schmitt. — On the action of ethyl mercaptan on diazo-com- 

 pounds, by the same. — On a curious occurrence of tape-worms, 

 by Herr Ebert. — On a Chinese work on insects, by C. F. Seidel. 

 —On the origin of organic life upon the earth, by Dr. Steil. — 

 On the red gneiss near Freiberg in Saxony, by Dr. Geinitz. — On 

 the natural history of the Caucasus cotmtries, by Dr. Oscar 

 Schneider. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, January 30. — "On the determination of the 

 Rate of Vibration of Tuning Forks,"by Herbert McLeod, F.C.S., 

 and George Sydenham Clarke, Lieut. R.E. Communicated by 

 Lord Rayleigh, F.R.S. 



The paper contains a description' of some experiments made 

 w ith a view to determine the absolute pitch of tuning forks by 

 means of a method proposed by the writers in a previous paper 

 (Proc. Roy. Soc., 1877, xxvi. 162). 



It commences with a description of the time-measurer adopted, 

 consisting of a compensated pendulum, worked by electricity. 



the impulse being given by a driver depending for its action on 

 gravity alone. The pendulum is arranged to give second con- 

 tacts, driving a clock-wheel with sixty teeth. This wheel has a 

 platinum pin giving minute contacts, but it is used merely as a 

 switch, the circuit being closed by the pendulum itself. The 

 current works a relay, and closes the circuit required. 



The tuning-fork apparatus consists of a brass drum resting on 

 friction-wheels, and driven by a weight and train. Uniformity 

 of motion being of great importance, an air-regxUator, consisting 

 of a fan inclosed in the lower compartment of a cylindrical box, 

 is employed. By means of a diaphragm and vanes the fan can 

 be made to do more or less work by pumping air firom the lower 

 into the upper compartment. The fan spindle carries a pulley 

 driven by a thread passing round the drum. 



Round one end of the drum are wrapped strips of paper on 

 which white equidistant lines have been so rul«l that they are 

 parallel to the axis of the dnmi when the strips are in position. 

 The strip most frequently used has 486 lines round the complete 

 circumference of the drum. Opposite this graduated strip is placed 

 a microscope with its axis horizontal. In the substage is placed a 

 2" objective, producing an image of the gradviations at the focus 

 of the object-glass of the instrument. At the common focus of 

 the two lenses is placed the tuning-fork, the stem of which is 

 held vertical in a vice. The fork is partially inclosed in a glass 

 case, and is so adjusted that the image of one of its limbs seems 

 to cut the image of the graduations at right angles. The fork is 

 set in motion by a suspended double-bass bow. If, when the 

 fork is in vibration the drum is made to rotate with such a 

 velocity that one of the graduations passes over the interval be- 

 tween two adjacent graduations in the time of one vibration of 

 the fork, a stationary wave is seen of length equal to the length 

 of that interval. To determine the number of vibrations of the 

 fork in a given time, it is only necessary, therefore, to be able to 

 count the number of graduations which pass in that period. As 

 a perfectly uniform rotation has not been obtained, a r^idator 

 under the control of the operator is employed. This consists 

 merely of a piece of string which passes round the axis of the 

 drum, and also round a pulley which can be turned by the 

 operator's left hand. An upward or downward motion of the 

 wave denotes that the drum is going too fast or too slow, and by 

 means of the pulley a gentle check or acceleration su£5cient to 

 keep the wave steady is given to the drum. 



An electric counter gives the number of complete revolutions 

 accomplished by the drum in any given period, and a fine-pointed 

 tube, containing magenta, is carried by a saddle above the drum, 

 and being actuated by an electro-magnet, makes a dot on a piece 

 of white paper wrapped round the dnun at the b^inning and 

 end of the experiment. The distance apart of these dots gives 

 the additional fraction of a revolution accomplished by the drum 

 dturing the period of the experiment. Electric circuits are so 

 arranged that a reverser txuned a few seconds before the minute 

 at which it is intended to begin the experiment, causes a current 

 to be sent exactly at that minute by the clock relay, which starts 

 the electric counter, and also makes a dot on the drum. Just 

 before the expiration of the last minute of the experiment the 

 reverser is turned in the opposite direction, and at the expiration 

 of that minute the counter is stopped, and a second mark made 

 on the dram. 



Some of the resxilts obtained with different forks are given. 



The results of further experiments made to determine the effect 

 of temperature, of continuous and intermittent bowing, and of 

 the mode of fixing the fork are appended. 



An optical method by which two slightly dissonant forks may 

 be compared without altering the period of either, is described. 



Figures and diagrams folly explaining the apparatus employed 

 accompany the paper. 



February 13. — "Note on the Development of the Olfactory 

 Nerve and Olfactory Organ of Vertebrates." By A. Milnes 

 Marshall, M.A., D.Sc, Fellow of St. John's College, Cam- 

 bridge. Communicated by W. S. Savory, F.R.S. , Surgeon to, 

 and Lecturer on Surgery at, St. Bartholomew's HospitaL 



In the course of an investigation into the development of the 

 cranial nerves of the chick, certain facts came to light indicating 

 that the olfactory nerve, instead of being, as usually described, 

 a structure differing totally in its mode of origin from all the 

 other nerves in the body, in reality " exactly corresponds in mode 

 of development with the other cranial nerves, and with the pos- 

 terior roots of the spinal nerves." ^ 



' Proc. Roy. Soc, March 8, 1877, p. 50, and Quarterly Jomnuil of 

 Mia oscopical Science, January, 187*, pp. 17-23. 



