John Phillips to Faraday   5 December 1850

St Mary’s Lodge | York | Dec. 5 1850

My dear Faraday

Many thanks for your kind explanations of the meaning which ought to be attached to your lines of magnetic force, which I quite comprehend and (I think) see the bearings of.

Believing from the interest you appear to take in the question of Aurora - that you may be induced to try to bring that recusant within the pale of your magnetism, I will venture to send you my little Hypothesis derived from my many nights of gazing, & not a few of needle scrutinizing.

In my little page¹ only the peculiar Aurora of 1847 is described, but to comprehend my view fully it is necessary to take two cases.

1. The Auroral Arch, really weak, viz a narrow white ‘ring of light’ stretched across the dipping needle like the ordinary conjunctive wire. This moves from NNW to SSE, at a pretty regular rate. I esteem it to be a simple Electrical Current.

2. The Beam, which is commonly seen at a great distance & seen edgeways, appears like a brush or pencil of light, parallel to the Dipping Needle, of the plane or nearly so. But I apprehend this appearance is not to be trusted altogether. I suppose that the beam when it is viewed from beneath has a different aspect, & such a structure as to justify me in regarding it as an Electrical Magnet. When the sky is so favorably covered by Aurora as in 1847 & 1834, the great area of light is found to be subject to intermittence, as

This is as the swift flashing, or curtain waving.

or

This is the wonderful ‘Pulsation’ (so called by Airy² & self independently) and I conceive that the Electric discharges thus subject to fits of alternate brightness & darkness, in a line

parallel to dipping needle may have the effect of interrupted spirals - or continuous spirals, & affect the Needle - though when looked at edgeways they seem (at 70 miles distance) to be like travelling pencils of light.

They certainly lie parallel to the dipping needle, & some (or probably all) affect the Compass; this could hardly be if they were simple brushes of light - for in that case they have no business to look to the same Star as the Dipping Needle & the Compass ought not to see them. The simple Arch or ring of Auroral Light is rather uncommon.

See what a penalty you pay for being famous!

I have just refixed my old Suspension Magnet, in hopes to get some further evidence of the influence of Aurora on it this winter.

My Sister³ joins in kind Comps to Mrs Faraday with your faithful friend | John Phillips