Record. xxxvii 



could be accounted for by an increase in the permeability of 

 the long explosion chamber. The deflection reverses when 

 the field is reversed. The hot gases liberated in the explo- 

 sion are all diamagnetic, and tend to decrease the observed 

 effect. In two cases the galvanometer deflection was in the 

 opposite direction from that stated above, and this is being 

 further inquired into. When seven tubes between the two 

 coils are simultaneously exploded, only slight effects could be 

 obtained, and these deflections are wavering, or to and fro, 

 in character. A wire was threaded through the inner com- 

 bustion tube, through which a current of three amperes was 

 pasaed. This circuit was opened and closed with no visible 

 effect. The galvanometer circuit is shielded by tin-foil, which 

 is also connected with the explosion tube, and grounded. 

 Sparks an inch long to the tin-foil produce no result. When 

 the explosion tube is removed from the transformer, and taken 

 near the galvanometer, or the storage battery, no deflection 

 is produced by the explosion. 



An explosive mixture of gases from water electrolysis under 

 atmospheric pressure produces a much less violent explosion, 

 and produces a correspondingly less effect. The scale reading 

 of the galvanometer changes by over twenty divisions with 

 the heaviest explosions, and an exciting current of 0.6 ampere. 

 With smaller explosions or feebler current, the effect is 

 diminished. No deflections can be produced by striking the 

 table upon which the transformer rests, or by striking the 

 transformer itself, even when it moves slightly under the 

 blow. The secondary and primary coils are held rigidly in 

 fixed position with respect to each other. 



Arrangements have now been made to place the explosion 

 tube in the focal line of a parabolic cylinder of metal, the 

 galvanometer coil being in the focal line of a similar 

 mirror. Either or both are to be surrounded by an exciting: 

 coil. 



This line of research was suggested by Young's account of 

 his observation of five solar outbursts in 1872, which were 

 each accompanied by sharp fluctuations in the magnetic trac- 

 ings at Kew and Stony hurst. Since the experiments began, 



