638 REPORT— 1900. 



freijuencies, is a continuous one. There is also a continuity of effect on all forms 

 of inorganic matter, similar effects being produced not only (I) in all elementary- 

 substances — metals, non-metals, and metalloids^but also (2) in metallic compounds, 

 such as the chlorides, bromides, iodides, oxides, and sulphides. 



Comparisons are next made of the molecular response in both inorganic and 

 living substances under varying conditions : — 



1 . On the effect of moderate stimulus. 



2. On the eti'ect of maximum stimulus. 



•3. On the effect of superposition of medium stimuli — («) effect due to slow 

 intermittence ; (b) tetanic eB'ect due to rapid intermittence. 



4. Ou the opposite effect due to strong and feeble stimulus. 



5. On the physical theory of ' fatigue ' in inorganic and living substances. 

 (). Ou the various means of rapidly removing fatigue. 



7. On the effect of injection of various substances which act as ' poisons.' 



lu all the above cases the curves for both living and inorganic substances are 

 found to be similar. 



The author next explains a theory of vision, and describes an artificial retina ; 

 the various effects of radiation on this artificial retina explain many obscure 

 phenomena of vision. 



Parallel experiments are then described with the artificial and the real 

 retina : — 



1. On the effect of short exposure to the action of radiation. 



2. On the effect of intermittent radiation ; on the question of the presence or 

 absence of ' flicker ' depending on the intensity of radiation and also on the 

 rapidity of intermittence. 



3. On the peculiarity of the visual sensation curve, as explained by the curve 

 of effect ou the artificial retina. 



4. Ou the different elements of retinal fatigue. 



5. On certain curious reversal effects. 



C. On after-oscillation and visual recuiTence. 



7. On the novel phenomenon of binocular alternation of vision, and on the 

 analysis of superposed images by alternate after-vision. 



8. On the persistence of retinal oscillation, and its continuity witli the phe- 

 nomenon of memory. 



In all the phenomena described above there is seen a remarkable similarity 

 of effect of external stimulus on both living and non-living forms of matter. It is 

 difficult to draw a line and say, ' Here the physical process ends and the physio- 

 logical process begins,' or ' These are the lines of demarcation that separate the 

 phj'sical, the physiological, and the beginning of psychical processes.' Iso such 

 arbitrary lines can be drawn, there being no abrupt break of continuity. 



4. Wireless Telephony. By Sir William Henry Preece, K.C.B., F.R.S. 



The first experiments in this direction were made in the month of February 

 1894, across Loch Ness in the Highlands. Ou that occasion trials were made t'"> 

 determine the laws governing the transmission of Morse signals by the electro- 

 magnetic method of wireless telegraph}-, which has formed the subject of frequent 

 reports to this Section since 1884; two parallel wires well earthed were taken, one 

 on each side of the lake, and arrangements were made by means of which the wires 

 could be systematically shortened with a view of ascertaining the minimum lengtli 

 necessary to record satisfactory signals. It occurred to Mr. Gavey, who was 

 experimenting, to compare telephonic with telegraphic signals, i.e., to ascertain 

 whether articulate speech could be maintained under the same conditions as Morse 

 signalling. The trials showed that it was possible to exchange speech across the 

 Loch at an average distance of 1'3 mile between the parallel wires when the 

 l^^no-th of tho wires themselves was reduced to four miles ou each siac of tiie 

 water. 



