186 SARSEN, BASALT AND OTHER BOULDERS IN ESSEX.
Sr
I am heartily sorry it is so late as half an hour after 6 or near
7, and that 2 Gentlemen my Friends are this minute dropped in,
y' I cannot have the pleasure of seeing the Flight of Ants as I now
assuredly call them from your Specimen. I hope your health
will permit you to observe nicely wch way they come from, & which
way steer their course ; or do you think that the Ant hills about
you can afford a sufficient Number for such an appearance ? Be
pleased to observe all particulars possible, wch I know will be
extreamly gratefull to ye Society. The day I heard (by Dr. Sloane)
you were in town, Mr. Pettiver & I dined wth Dr., & had all of
us a Contest what Species the' vast Flight at London last year was
of. They were enclined to think Ichneumons : but your Specimen
proves the contrary plainly. I am very sorry to hear that you are
not in the best circumstances of health, wch I heartily wish being
Sr
Your much obliged humble servt
W. Derham
Be pleased to order your servts to look out for them to morrow
morning.
The Ichneumon is a small parasitic hymenopterous insect.
SARSEN, BASALT AND OTHER BOULDERS
IN ESSEX.
BY A. E. SALTER, D.SC., F.G.S.
[Read 17th December, 1910. Revised, 1914.]
WHILE studying the Drifts of East Anglia, it has been
my custom for several years past to note the position,
approximate size and composition of any large or interesting
Boulders, which I came across during my many traverses
in that region.
Prof. Bonney, in his Presidential Address to the British
Association at Sheffield (1910), re-opened the question of the
origin of the Drift. The evidence obtainable in East Anglia
should have an important bearing upon this, especially that
concerning large boulders, the present positions of which are
in many cases far removed from their source of origin.
Recently, I gathered together all the evidence I could con-
cerning the boulders in Hertfordshire. This paper concerns
those already found in Essex, and it is hoped that the subject
will be again taken up, especially in the outlying parts of the