502 



NATURE 



\_March 22, 1888 



Motacilla yan-elli \ MotacilHd*. 



Biidytes rayi ) 



Todiis viridis. Todidae. 



Steatornis caripensis. Steatornidae. 



Schizorhis ) 



Mzi.sophaga \ Musophagidjc. 



Corythaix ) 



DiclwlopJms. Dicholophidffi. 



Frocellaria \ 



^, , ., >ProcelIarid£e. 



Thalassidroma C 



Diomedea, &=€. ) 



Larus, var. spec. Laridae, .. 



Tachypetes. Tachypetidae. ( 



Another more partial remnant is seen in the Coracomorphae 

 •or Passerine birds generally, which together make up nearly 

 half the number of known birds. 



A distinct nucleus representing the post-palatine region of 

 the Frog's skull reappears in the Crow and the Sparrow, and 

 in all the Passerines, as far as they have been worked out. It 

 lies outside the hinder part]bf the normal parosteal palatine bone, 

 becomes a solid ear-shaped tract of hyaline cartilage, acquires 

 its own osseous (endosteal) centre, and this, when ossified, 

 coalesces with the normal palatine bone. 



These facts, and many others that could be mentioned, make it 

 ■evident that, in seeking for a clue to the uprise of the Feathered 

 Fowl, we may leave out of immediate consideration all the exist- 

 ing types of Reptilia : ancient Amphibians, or Reptiles just rising 

 out of Amphibian lowliness, are the forms that alone will help us 

 in this search. We do get some light upon the Reptilian relation- 

 ship of Birds, but.it is at best a scattered light ; the head of a Bird 

 is like that of the Ichthyosmirus in its great facial elongation, 

 the neck- and limb-regions of a Bird are those of a Plesiosaunis, 

 whilst the hips and legs are like those of the Ornithoscelida. 



But these are not all, or nearly all, the vestigial structures that 

 may be seen in the Bird's skull, to say nothing of the skeleton 

 generally ; ^ they are sufficient, however, to justify the assumption 

 that Birds arose, by secular transformation, either from the 

 lowest and most ancient of the true Reptiles, or equally with 

 Reptiles from archaic Amphibia, low in structure, but full of 

 potential excellence, and ready, pro j-e nata, to become Reptile, 

 Bird, or even Mammal, as the case might be. 



Physical Society, March lo. — Prof. Reinold, President, in 

 the chair. — Mr. G. L. Addenbrooke exhibited and described a 

 compact form of reflecting galvanometer, lamp, and scale, which 

 he has designed as a portable commercial instrument, and also a 

 modified Post Office Wheatstone's bridge. — Mr. E. C. Rimington 

 read a paper on the measurement of the power supplied to the 

 primary coil of a transformer. The first part of the paper con- 

 tains a proof of a formula given by Prof. Ayrton at a recent 

 meeting of the Society of Telegraph-Engineers for measuring 

 the power given to a transformer by using a Siemens's watt- 

 meter, and the disadvantages of the method are enumerated. A 

 method is then described in which a high-resistance dynamometer 

 is used. One coil of the dynamometer is placed as a shunt to 

 the primary coil, and the other as a shunt to a known induction - 

 less resistance, R, placed in series with the primary. The time 

 constants of the dynamometer coils are made equal by adding an 

 inductionless resistance to the one having the greatest time 

 constant. Thus arranged the difference of phase between the 

 •currents in the dynanometer coils is the same as that between 

 the P.D. and current in the primary of the transformer. The 

 mean jDower, /„,!, is shown to be 



A 



K 



= I 5 (I + tan2,^i). 



•where - is the constant of the dynamometer for watts, S the 



reading of the torsion head, and </>! the lag angle of the currents 

 in the coils of the dynamometer which can be determined from 

 their time constant and periodic time. The best method of 

 ari-anging the dynamometer in order that R may be as small 

 as possible is discussed. Prof. Ayrton pointed out that the 

 formula first referred to by the author was given to show %vhy a 

 luatt-meter should not be used, and that the method suggested by 



' As regards the skeleton of the manus and pes, the indications of at least 

 five carpals (t'wo of these in some types undergoing further subdivision), 

 three small additional rudiments of digital rays in the manus, five tarsals, 

 and a rudiment of the fifth metatarsal, are all important facts bear ng upon 

 this subject. 



Mr. Rimington was a modification of the well-known electro- 

 meter method, but with an additional serious objection, that the 

 periodic lime must be known. He also described a direct- 

 reading method of using an electrometer, on ordinary transformer 

 circuits, suggested to him by Mr. Sayers. Mr. Blakesley thought 

 tlie above formula, given by Mr. Rimington, would only be 

 true where there is no iron in the circuit. He described a 

 method of determining the power by observations on two low- 

 resistance dynamometers, one of which is placed in the primary cir- 

 cuit. Of the other dynamometer, one coil is placed in the primary 

 and the other in the secondary circuit. The power is given by 



/;„ = Ka^i\ 4- ;-2 



Ca, 



where i\, r.^, vi, n are the resistances and nui^ibers of 

 convolutions of the primary and secondary coils, A and 

 C the constants of the dynamometers, and Oj, a..^ their read- 

 ing. A geometrical construction from which the formula 

 is deduced was given. Mr. Sumpner said all the formulaj 

 at present obtained were founded on the assumptions that 

 the induction coefficients of a transformer under working condi- 

 tions are constant, but, in a paper to be brought before the 

 Society shortly, he hoped to show these assumptions to be 

 erroneous. In replying, Mr. Rimington said, if the periodic 

 time was not known beforehand, it could easily be determined 

 from the note given out by a telephone placed near the trans- 

 former. — On the magnetic circuit in dynamo machines, by Prof. 

 W. E. Ayrton and Prof. J. Perry. An abstract was read by 

 Prof. Perry. The authors have worked out a number of 

 formulae for dynamo machines, involving the thickness, t, of the 

 armature winding, and o the highest permanent current density 

 per square centimetre of cross section of that winding. One of 

 them is 



lo** 



where W = highest permanent output in watts, v = circumfer- 

 ential velocity, and N = total induction through the armature. 

 As the winding is thin, to' = q"', a constant. For the best 

 modern machines, which do not get too hot, q has a value of 

 about 288. It is shown that the best permanent output is a 

 maximum when the magnetic resistance of the space occupied 

 by the armature winding is equal to all the other magnetic 

 resistance in the circuit, and the best machines are found to 

 satisfy this condition. From this important result the character- 

 istic of such a dynamo can be drawn with considerable accuracy. 

 For small inductions the air resistance only need be considered, 

 and a line drawn on squared paper connecting N and S'A', 

 satisfying 



j^ _ 47rS'A/ _^ l{d -f t 



10 * «2 



gives the first part of the characteristic, where S'A' = 

 ampere-turns, rt' =; clearance, and a^, = the area of the pole 

 pieces exposed to the armature (increased by a fringe of 0"8 

 \d + t) all round). From the maximum value of N (viz. a^^^ 

 where a-^ = area of diametral section of iron in armature, and 

 01 = maximum induction (17,000 to 18,000), find the value of 

 S'A' from the formula 



N 



4irS'A' 



4i 



and plot the values of N and S'A' as the co-ordinates of a point. 

 A curve drawn through this point to touch the line first drawn, 

 at a point corresponding with N = ^aj/Sj will not differ materi- 

 ally from the characteristic of the constructed machine. — A note 

 on the employment of an electro-dynamometer for determining 

 the difference of phase of two harmonic currents of electricity, 

 by Mr. T. H. Blakesley, was taken as read. This is a claim of 

 priority for a method published by the author in the Electrician 

 of October 2, 1885, which has recently been described and 

 claimed as the invention of Prof. Ferraris, in a paper communi- 

 cated to the Royal Academy of Science of Turin. In a book 

 on "Alternating Currents," published at the end of 1885, Mr. 

 Blakesley shows how the method can be used for determining 

 induction coefficients and capacities. 



Chemical Society, March r. — Mr. :W. Crookes, F.R.S., 

 in the chair. — The following papers were read : — The origin of 

 colour and the constitution of colouring matters, by Prof. H. E. 

 Armstrong, F.R. S. The majority of compounds, especially 

 those of carbon, are colourless ; and in the case of elements 



