SCIENTIFIC SUMMARY. 
103 
The Microscopical Aspects of Circular Solar Spectra. — These are given in 
a paper in the “Monthly Microscopical Journal ” October, by Dr. Pigott, 
F.R.S., who thus tabulates them: — “1. As stated in the paper ‘ On a 
Searcher for Aplanatic Images/ regarding a convex lens as under-corrected, 
under-correction is shown by the appearance of the rings below or beyond 
the focal point and evanishment into mist above it. 2. Similarity in the 
rings on both sides (with change of colour also) denotes a balance more or 
less delicate of the aberrations. 3. An excentric position of the solar disk 
and a crowding of the rings more closely on one side than the other of the 
circular spectrum denotes parallelism, but non-coincidence of the axes of the 
convergent and divergent pencils. 4. Rare and beautiful forms resembling 
parachutes, vases, or comets, made up of ellipsoid, parabolic, or hyperbolic 
diffraction-lines, denote obliquity. 5. Their form depends on the nature of the 
aberrations present, and the mode of arranging the axis of the cone of rays 
forming the solar disk. 6. Inaccurate centering of the component lenses, 
either at the heliostat or in the observing or miniature-making objectives, 
is shown by 1 excentric turning ’ patterns and the appearance of two or 
several central disks at the smallest focal spectrum. 7. The apparatus ne- 
cessary to display these brilliant phenomena must be exceptionally heavy 
and steady, and the fine adjustment should have a screw 100 threads to 
the inch, as the ten-thousandth of an inch in the axis of observation 
completely changes the aspect of the phenomena.” 
List of Papers on Microscopic Anatomy published in the u Monthly 
Microscopical Journal ” for October, November, December. There were : — 
A Description of the Thread-worm, Filaria immitis, occasionally infesting 
the Vascular System of the Dog, and remarks on the same relative to 
Hsematozoa in General, and the Filaria in the Human Blood. By 
Francis H. Welch, F.R.C.S.E., Assistant Professor of Pathology, Army 
Medical School, Netley, Southampton. — Researches in Circular Solar 
Spectra, applied to test Residuary Aberration in Microscopes and 
Telescopes ; and the Construction of a Compensating Eye-piece, being a 
Sequel to the Paper on a Searcher for Aplanatic Images. By G. West 
Royston-Pigott, M.A., M.D., Cantab., Memb. Roy. Col. Phys., 
Fellow of the Camb. Phil. Soc., the Royal Ast. Society, &c., and late 
Fellow of St. Peter’s 'iC oil., Cambridge. — A New Freezing Microtome. 
By William Rutherford, M.D., Professor of Physiology, King’s College, 
London. — On an Organism found in Fresh-pond Water. By R. L. 
Maddox, M.D., H.F.R.M.S. — A Description of some New Species of 
Diatomacese. By F. Kitton, Norwich. — Nematophycus or Prototaxites ? 
By William Carruthers, F.R.S. — On Immersion Objectives of greater 
Aperture than corresponds to the Maximum possible for Dry Objectives. 
By Assistant-Surgeon J. J. Woodward, U.S. Army. — On Bog Mosses. 
By R. Braithwaite, M.D., F.L.S. — On the Investigation of Microscopic 
Forms by means of the Images which they furnish of External 
Objects, with some Practical Applications. By Prof. 0. N. Rood, of 
Troy, N.Y. — Further Researches into the Life History of the Monads. 
By W. H. Dallinger, F.R.M.S., and J. Drysdale, M.D. — Some Remarks 
on the art of Photographing Microscopic Objects. By Alfred Sanders, 
M.R.C.S., F.L.S., and F.R.M.S., Lecturer on Comparative Anatomy at 
