1G4 
PROFESSOR OLIVER LODGE ON THE ABSENCE OF 
of the residual irreversible shift observable at high speeds, when all kinds of 
mechanical and thermal disturbance have been apparently eliminated. 
TJie question of Electrification. 
Although it must now be taken that such masses of matter as we had been dealing 
with are incompetent to disturb the ether in a rotational manner (for, as has been 
emphasised in the previous memoir, irrotational motion of a single-valued kind could 
not be detected by interference or any other optical experiments, since such motion 
in no way affects either the path or the speed of a ray), and although further it has 
nov^ been shown that the conveyance of a magnetic field by moving matter confers 
no power of gripping the ether, yet it was thought possible that electrification might 
do it; because an oscillatory charge certainly radiates wave motion into the ether. 
And although radiation is not any knowir kind of mechanical disturbance, but is 
concerned with the ether’s electrical properties, and need not necessarily involve any¬ 
thing analogous to etherial viscosity even in the neighbourhood of matter, 3 mt it was 
thought possible that electric charge, being as it were the connexion between ether 
and matter, might confer upon a matei’ial body some power of gripping and rotation- 
ally carrying forward the ether in a C[uasi-viscous manner. At any rate, whatever 
reason could be urged for or against such a connexion, it was desirable to bring it to 
the test of experiment and superpose an electric field u])on the moving disks. 
The natural plan for electrifying the disks would seem to be to make one of the 
disks positive and the other negative, but after consideration it was found impractic¬ 
able to insulate the existing disks satisfactoril}"; and a third disk half way between 
the other two was contemplated. This might possibly' have been stationary and 
independently supported, but some preliminary experiments with a plate thus held 
sliowed that in the draught of air it developed some warmth and interfered with the 
Fig. 7. 
Avrangement of tlie insnlatecl steel disk between the oilier two, showing the mode of electrical 
connexion, witli an axial stud touching a Voss machine terminal. 
fringes ; so a rotating disk, clamped in insulating washers between the other two, 
was decided on, and made as shown in fig. 7. The new disk was made an inch 
smaller in diameter than the others, but otherwise it was just like them. Connexions 
were arranged through insulating holes for the supply of electricit}" near the axle 
