Dec. 15, 1881 | 
NATURE 
t57 
these sudden squalls which lash into a tempest of waves 
what is but a mere patch or narrow lane of sea, while all 
round remains like a sheet of glass, the squall being only 
the lowermost part of the gyrating column of a slanting 
whirlwind. Nothing is more surprising to the landsman 
who encounters one of these squalls for the first time than 
to see a mere bit of sea lashed into a tempest by say an 
east wind in which no sail can live, while but a short way 
to leeward other vessels are seen either under a good- 
going breeze or in calm water, altogether untouched by 
the tempest, which seems to blow directly to them, but 
which strangely never reaches them. 
In examining cyclones, phenomena occasionally present 
themselves which strongly suggest the idea that they in- 
clude within their circuit, as an independent meteor, the 
whirlwind or the tornado, the phenomena in question 
being most frequently met with in those cyclones which 
present, in close continuity, masses of air differing very 
widely from each other in temperature and humidity. .Of 
such cyclones the great storm of October 14 last appears 
to be one. On that occasion the changes of temperature 
and humidity were sharp and sudden, particularly from 
the Grampians to the Cheviots, the great fall occurring 
when the wind changed to northward. As we have 
already stated (NATURE, vol. xxiv. p. 585), off the Ber- 
wickshire coast the darkness accompanying the changes 
of wind, temperature, and humidity was denser and more 
threatening than elsewhere, and almost simultaneously 
with the approach of these changes, a hurricane, or rather 
tornado, broke out with a devouring energy which bore 
everything before it. Thetornado-character of the storm 
off Eyemouth is shown by the accounts of some of the 
survivors, who describe the wind as blowing straight 
down from the sky with an impetuosity so vehement and 
overmastering that the sea for some extent was beaten 
down flat into a stretch of seething foam, in which many 
boats sank as if driven down beneath the foam by the 
wind, while outside this tract the waves seemed to be 
driven up to a height absolutely appalling, which in their 
turn engulfed many of the boats yet remaining. Similar 
seas, with level wastes of seething foam, bounded imme- 
diately by waves of a height and threatening aspect 
never before witnessed, were encountered by several well- 
appointed steamers out in the middle of the North Sea 
during this storm, thus confirming the observations of the 
Eyemouth fishermen. These facts seem to point to one 
or perhaps more tornadoes of no inconsiderable dimen- 
sions, with slanting columns, the terrific force of the gyra- 
tions of whose lower extremities played no inconspicuous 
part in the devastation wrought during the continuance of 
this memorable storm, 
(To be continued.) 
SIR DAVID BREWSTER’S SCIENTIFIC WORK 
ur thirteen years ago there passed away from the 
roll of living scientific worthies one whose name will 
ever hold a high place for the variety and scope of the 
researches carried out with untiring zeal through a long 
and useful life. Since our last number the centenary of 
Sir David Brewster's birth has been commemorated in 
Edinburgh, and the occurrence forms a fitting opportunity 
to review briefly his multifarious work in the light of the 
science of to-day. Sir David Brewster was born in 1781. 
He must therefore have been twenty-five years of age at 
the date when his first published scientific memoir, 
entitled “ Remarks on Achromatic Eyepieces”’ (published 
in Wicholson’s Fournal), saw the light. Until 1867 he 
continued actively to pursue scientific researches. Whilst 
his literary works are of themselves amply sufficient to 
cause the name of Brewster to be handed down to pos- 
terity, the long list of four hundred original memoirs 
which appears in his name in the Royal Society’s Cata- 
logue shows with what unremitting ardour the fire of dis- 
covery burned within his breast. 
In the domain of Physical Optics Brewster was an 
eager and successful worker: and his industry was re- 
warded by a series of brilliant experimental discoveries. 
The genius of Young, the keen perception and quick 
acumen of Malus, and the trained intellect of Arago had 
been concentrated on this hitherto neglected department 
of science. But Brewster, who cannot be said to have 
possessed, either by birth or education, the powers of any 
of these investigators, discovered more than all of them 
put together, and by diligent observation unravelled 
complicated phenomena which baffled their powers. 
In 1812, having heard of Malus’s. celebrated discovery 
of the polarisation of light by reflection, he took up the 
study of polarisation, and in the course of the next two 
years advanced our knowledge in various directions. He 
discovered the property of the agate to give a single 
polarised image; the polarisation of the rainbow; the 
polarisation tints in thin plates of crystal; the so-called 
Cepolarising power of mineral and other substances ; and 
the partial polarisation produced by metals. 
These discoveries he followed up immediately by 
several of equal interest. He observed the double 
system of elliptical rings of colour in topaz, and sub- 
sequently investigated the appearances presented hy 
other crystals, both monaxial and biaxial in convergent 
polarised light. He not only discovered but determined 
the law of the partial polarisation effected by transmitting 
light obliquely through a bundle of thin plates of mica or 
glass. Meantime he was actively prosecuting literary 
work. His “New Philosophical Instruments,” published 
in 1813, contained a great deal of matter new in the 
science of optics, the results of original research. Hither- 
to in tables of the refractive index of bodies diamond had 
stood at the head, and ice at the foot of the list. But 
Brewster showed that realgar and chromate of lead 
exceed the diamond in refractive power, whilst fluorspar, 
cyolite, and tabashear fall below ice both in refractive 
and in dispersive power. 
During these and the subsequent years the disturbed 
relations between Great Britain and France prevented 
the workers in science on opposite sides of the Channel 
from learning what progress was being made, with the 
result that many of Brewster’s discoveries were indepen- 
dently made by others. Thus Malus anticipated Brewster 
in the discovery of the “depolarising’’ effect of mica 
films, of the partial polarisation of metals, and of the 
polarisation effected by bundles of thin plates, though 
he missed the law of the last phenomenon. Arago 
also anticipated Brewster in finding the colours of thin 
crystal plates in polarised light. In 1814 and 1815 
Brewster discovered a new relation of polarised light, 
namely, that existing between the ray and the state of 
mechanical strain of the body through which it passed. 
He observed that heated glass exhibited coloured tints in 
polarised light, and that Rupert’s drops did the same. 
Subsequently he produced both double refraction and 
chromatic polarisation in soft and indurated jellies, in 
horn, and in a variety of animal and vegetable bodies, 
particularly in the crystalline lens of the eyes of animals, 
whose structure is thereby revealed. The most important 
of these early researches was undoubtedly the law connect- 
ing the angle of maximum polarisation by reflection with the 
refractive index of the body. The difficulty of establishing 
such a lawwas in Brewster’s case enhanced by the circum- 
stance that his mind was nota mathematical one. Witha 
skill that rose superior to the defects of apparatus, and with 
an unflagging patience at which one can only marvel, he 
scrutinised with minute care every fragment of mineral 
in the cabinets of his scientific acquaintances. By this 
means he constructed tables of refractive and dispersive 
powers and of the polarising angles ofthe various reflecting 
surfaces. And from these two sets of data he brought out 
