May 22, 1879] 



NATURE 



85 



merely transitory change, ten full pulsations were in the 

 second case (No. 3) allowed to elapse after the complete 

 closure of the three large vessels above-named, before the 

 second tracing was taken, and in the third trial (No. 4) 

 thirty beats were steadily counted with the vessels 

 occluded, before the second tracing was obtained. 

 Beyond this I did not feel justified in going, for fear of 

 phlebitic or thrombotic accidents. It will be seen, how- 

 ever, that the change of character in the wave becomes 

 decidedly more marked in each succeeding instance 

 than in that preceding it. [It consists roughly in 

 the total obliteration of the dicrotic wave termed the 

 "aortic notch." Accompanying this is an increase 

 of rapidity and suddenness in the line of ascent, 

 which, from being nearly vertical in the uncom- 

 pressed, bends distinctly backwards in the compressed 

 tracings, thus reproducing the circular arc in which the 

 index of the sphygmograph travels. The latter fact 

 might have been anticipated, but the former is curious, 

 and I believe novel. The compressed tracings might be 

 mistaken by an observer not acquainted with their mode 

 of production, for those of a patient in whom the com- 

 petency of the aortic valves was gravely impaired, and 

 where the reflux of blood into the ventricle, which, in a 

 healthy condition is prevented by their sudden closure, 

 was freely taking place. . On the plausible supposition 

 that the dicrotic wave is a return undulation, a sort of 

 echo sent back from the distal extremity of the arterial 

 tree, it may be suggested that the great shortening thus 

 artificially produced in the wave-length of the fluid 

 undulation causes the primary and dicrotic waves to 

 merge into one another. 



I may say that neither of my patients felt any incon- 

 venience from the experiment, either during compression 

 or afterwards. An attempt was made to cut the internal 

 iliacs also out of circuit by compressing the abdominal 

 aorta before its bifurcation ; but though to a good 

 anatomist like Mr. Pitts the occlusion of this large vessel 

 was not difficult, it caused so much hiccup and respiratory 

 spasm as to render the continuity of the tracing uncertain. 



W. H. Stone 



THE ELECTRIC LIGHT 



■\1 rE have already referred to the Albert Hall Exhi- 

 • ' bition, and its important bearing on the progress 

 of electric lighting by bringing together the various 

 methods by which it has been proposed to utilise elec- 

 tricity for this purpose. Since then the newspapers have 

 brought us intimations of further progress which it is 

 stated Mr. Edison has made, and as our readers doubtless 

 know, he has taken out one or more patents for various 

 alleged improvements. We have borne, and will continue 

 to bear, willing testimony to the marvellous ingenuity of 

 Mr. Edison in his application of various scientific prin- 

 ciples, resulting in inventions that a year or two ago were 

 scarcely dreamt of. We cannot but have the sincerest 

 wish for Mr. Edison's success in whatever he puts his 

 hand to ; and his position as an inventor is so high that 

 he needs not to take any trouble to make it more exalted 

 by allowing exaggerated and misleading statements to go 

 forth as to what he is about to do. 



We have recently heard a great deal of Mr. Edison's 

 experiments and promises with reference to the electric 

 light. He startled the world in August last by announcing 

 a great discovery which was to revolutionise the modes of 

 artificial illumination at present in use, but we fear his 

 discovery turned out to be something very like a ridiculus 

 mus. Two of his patents have been published ; one con- 

 tains what we must deem a grave scientific error, the 

 other the best authorities consider a mere reproduction of 

 things that have been patented before by Staite, Harrison 

 and others. Up to the present, so far as we can make 

 out, he has done nothing new nor has he produced any- 



thing practical. The reports of newspaper interviewers 

 are scarcely worthy of attention. Mr. Edison himself 

 complains bitterly of their importunity and irrepressi- 

 bility ; but why, then, does he seem to stam ) them with 

 his approval by distributing their reports from his own 

 laboratory ? We cannot but think it a misfortune that he 

 has kept at arms' length the electricians of New York, 

 not one of whom, according to his own statement, has 

 been allowed to enter his laboratory. We are therefore 

 entirely dependent upon the New York press for our 

 knowledge of his progress. 



He has laid aside for the present his incandescent light 

 and is experimenting with the Wallace form — his reason 

 being that " everybody knows what the carbon lamp is, 

 and besides it is not my lamp." He is engaged upon a 

 new dynamo-machine — let us hope not his tuning-fork 

 arrangement — but for what reasons he has put aside such 

 perfect machines as the Siemens and the Gramme we are 

 not enlightened. Dr. Hopkinson has recently shown that 

 the Siemens' machine utilises 90 per cent, of the energy 

 thrown into it. The Gramme is not far behind this. 

 Mr. Edison can scarcely hope to improve on either. 

 Again, the Brush and Wallace-Farmer machines are very 

 efficient. Indeed, we scarcely want to improve the 

 machine for producing currents. It is the lamp that 

 needs the thought and work of the inventor, for no lamp 

 yet exists worthy of the name. 



The propagation by the daily press of scientific " dis- 

 coveries" hot from the brain before they are allowed to 

 be cooled down by the test of experiment is an invention 

 upon which we cannot compliment our American friends. 

 It does not conduce to the progress of science nor does it 

 redound to the credit of the discoverer. We are accus- 

 tomed on this side of the water to learn of new discoveries 

 through the medium of well prepared and carefully 

 digested papers submitted to one of our societies. There 

 are such societies in America, but the records of such 

 societies have to be searched in vain for any experiments 

 or discoveries of Mr. Edison. We think it is matter for 

 sincere regret that he prefers to promulgate what he con- 

 ceives to be new through "our special correspondent," 

 and the science dished up by these gentlemen is some- 

 thing wonderful to read. Thus says one paper : — 



" Being questioned as to the subdivision of the electric 

 light, the inventor said : ' The question is very simple. 

 If you take a lamp in which the voltaic arc is produced 

 from two carbon pencils, the more current you put on the 

 faster the pencils are consumed and the resistance offered 

 is lessened. There necessarily results a great waste of 

 power. If the lamp is limited to 250-candle-light, it costs 

 too much. By my plan the resistance is almost entirely 

 at the lamp. The resistance of the conductor is to the 

 resistance of the lamp as i to 100. The resistance of my 

 lamp is as 192 against i to the resistance of the carbon 

 lamp. You may consider the question most intelligently 

 by taking a gas-burner as an example. If you have a 

 half-inch gas-pipe and light the escaping gas without 

 putting on a burner, how much gas-light can you 

 get from an adjoining burner? Very little. But if you 

 put in the half-inch pipe a burner, with a pin-hole in it, 

 you get a light without interfering with other burners. 

 The same condition obtains in electric lighting. The 

 carbon lamp represents the half-inch gas-pipe ; the pin- 

 hole burner represents my lamp.' ' But is not the 

 electric current exhausted, not with regard to the resisting 

 agent, but according to the square of the distance tra- 

 velled?' 'No. If you are supplying a mile of wire 

 and then add another mile, the current will be weakened 

 equally throughout the whole line, but not to that extent. 

 If you keep on extending your line, you will have to make 

 your conductor thick and add more power.' ' How do 

 you propose to carry this theory into effect ? ' 'I shall 

 have, proceeding from the central station, where a steam- 

 engine and a series of dynamo-machines are placed, a 



