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Nov. i 0, I 8 70]
NA TURE
  Tested thus broadly and philosophically, the meteoric bom-
bard ment hypothesis appears in its true colours as a monstrous
physical absurdity.  It assumes a perpetual flow of solid masses
convging continuously from everywhere towards everywhere;
or otherwise a state of things which could only endure through
the time which these meteoric masses would occupy in travellin-g
the semi-distance between the neighbouring suns. These little
journeys ended, the interstellar space must, according to this
hypothesis, become a sterile vacuum, all the lights of heaven
must go out, eternal darkness must rest upon the face of the
deep, and everlasting death pervade the universe.
                                    W. MATTIEU WILLIAMS
                       The Cockroach
   I HAVE only to-day noticed the Rev. C. J. Robinson's letter on
this subject in your issue of the 29th Sept. A friend of mine,
whom I have known all my life, who occupied an important
trust as Bank Manager in India last year, and who is at present
home on sick leave, assures me that Dr. Norman Macleod is
wrong when he denies the nail-nibbling propensities of the cock-
roach. My friend had been in Kurachee for some time, and on
his journey from that town to Bombay by sea he was annoyed
one night in his berth by some insect crawling over his face
halt asleep and half awake he put up his hand to his face and
sent the insect to the foot of his berth.  Shortly after he was
awoke by a pain at his great toe, and on looking at it he dis-
covered that a cockroach had nibbled off all the nail down to
the quick.                                     JAMES DURIE
   Aberystwith, Oct. 8
 Were Cockroaches known to the Ancient Greeks and
                            Romans ?
   YOUR correspondent, Rev. C. J. Robinson, drew attention in
your columns (NATURE, Sept. 29) to the question whether these
troublesome insects were known to the Ancient Greeks and
Romans; he says, " there is a good deal to lead one to suppose
that the ,uvAaKpth mentioned by Aristotle, and the Blatta pis/ri-
norum of Latin writers was the same as our loathsome pest."
I think Mr. Robinson is mistaken in supposing that the AVAaKpLS
is mentioned by Aristotle, at least I can find no mention made
of this insect in the writings of the Stagirite.  The word
cuvAaKpLs, meaning some kind of insect, occurs in the fragments
of Aristophanes preserved by Pollux, who amongst other mean-
ings of the term gives the following one :-Cv C 1 Ev -r1 /vAcvL
ytyVL&d/EJ'OV, and then quotes this couplet from Aristophanes,
                'Iva uVVcTLJV ;;7rEp driaeoeaf' Ra,
              2KanA71vas 90-Ozre5, Kcal /uvAaKp[Bas.
 "where they may partake of the food of which they are fond,
 eating worms and my/ocrides. " It would not be possible to say
 what the LUXawcp'S here denotes, but from the creature being often
 produced in mills, it may possibly mean a " Cockroach," though
 a "'meal-worm" (i.e., the larva of the beetle, 7TeLb-io muwi/or)
 would suit equally well. '1'he Greeks, howvever, had a word which
 may well represent the Cockroach, thoughit is even here impossible
 to speak with certainty. The word, utA x. it is probable de-
 notes this insect. Ari.totle (Hist. Anim. viii. 19. § 4) uses the
 word once; he enumerates the si/phe amongst insects which cast
 their skins.  The Scholiast in the " Peace" of Aristophanes
 says the si/phe is an ill-smelling insect (8unvoW3uos). Aetius (8. 33.)
 speaks of " the fat of the stinking si/pAe which inhabits houses."
 The epigrammatist Evenus (Analect, i. p. i67) speaks of the
 sip~he of the booksellers' shops, and applies to it the epithets,
 page eating (a-EXLtflp4yos), destructive (,\w7j>T4epa), black-bodied
 (AiAatvXpws)."  Lucian speaks of the mere book collector as
 providing pastime for mice and habitations for srilphe, and cuffs
 his slaves for riot keeping the mice and si/phe away. (Advers.
 Indoct, iii. iz4, Ed. Hemsterhus). The Scholiast here gives a
 description of the silphe which Schneider with some reason refers
 to some kind of Lepisma. /Elian (H. A. i. 37) says that the
 .ilphe infest swallows' nests ; these cannot be cockroaches. Galen
 and Paulus Aegineta apply the epithet, 8fOUOvaai, to the silp/hai.
 Dioscorides (ii. 38) says that the inside of the si/he found in
 bake-houses when pounded with oil is good for pains in the ear.
This leads me to the Blatta of the Romans. " On pulling off,"
says Pliny, " the head of a blatta it gives forth a greasy sub-
stance, which, beaten up with oil of roses, is said to be wonder-
fully good for affections of the ears." He speaks of the disgusting
nature of this insect. one kind of which is known by the name of
AIyloecon, and found in mills (Nat. Hist. xxix. 39). In another
place (xi. 34) Pliny says, " It is the nature of the b/atta to seek
dark corners and to avoid the light; they are very often found
1k A Aanr:_l t-.L_  1 _I  A d -   '1' -   .1  I _  I, _7)
iii vauILS.  Aiccordirg to V irgil, m-te lignt-avoiding VWMT
find their way into bee-hives (Geor. iv. 243).  Horace (Sat.
ii. 3, I19) ridicules an old miser for sleeping on straw and
leaving his bed clothes in his chest, the food of blatted and
tineae,  "Blattarum  ac tinearum  Epule."  Martial (Lib. iv.
Ep. 37.) says unless his books are well put together they
become the prey of tineaz and b/att/a.
                 Constuictos nisi das mihi libellos
                 Admittam tineas trucesque blattas.
  From the above passages it will be seen that the b/atta was a
destructive insect to clothes, books, &c., that it avoided the light,
and was fond of warm places, that it frequented mills and ex-
uded a greasy substance from its head, that it was a disgusting
creature (probably in allusion to the smell) all of which par-
ticulars are true of cockroaches, and as there are many species
of the family, and are widely distributed over all parts of the
globe and must have been known to the ancients, I think there
is good reason for concluding that the cockroach was known to
the Greeks by the name of ALAp77, and to the Romans by that of
bla/at.                                     W. HOUGHTON
                    The Aurora Borealis
  I SHALL be obliged if you will put on record a few scattered
notes which I took of the splendid Aurora Borealis of October
25, seen from Arthingworth, Northamptonshire. When I first
observed it at half-past five P. Ai., a crimson glow extended in an
irregular band from N. N.E. to WV., most prominent at about
200 to 300 above the horizon. This increased in height and
breadth until it nearly reached a point S.W. of the zenith, and
about 15 \\T. N. \W. of the star Vega. At this time the northern
part of the sky was perfectly free from aurora; gradually that part
and the whole dome of the heavens, with the exception of a
section from  W. to nearly S., became filled with luminous
streamers. These, for about 20° on each side of N., were white,
the others crimson striped with white or rather greenish light,
but the green I believe to be an effect of contrast, as where
similar streamers were distant from the red light they were
white.
  The white or green steamers appeared to eclipse the red light,
they changed their size, shape, and position, while the red con-
tinued comparatively unchanged. There were also dark streamers
which, at first, I believed to be mere spaces without light, and
to be caused by the darkness beyond, but I became ultimately
convinced (as far as one could be convinced by appearances so
subject to illusion) that they formed a part of the phenomenon
itself. These streamers or long brushes could be seen beyond
and clear of the luminous portion of the aurora, leaving the normal
light of the sky between them and it, and hanging like long
horse-tails, or like the fringes of rain seen on the edges of a
distant rain cloud; changing their shape and position just as the
luminous streamers are seen to do.
  The most remarkable part of the phenomenon, however, was
the circle of sky, or what may be called the pole of the aurora,
to xvhich the streamers converged.  It app eared to embrace
about from 70 to io0 of space. To an ordinary observer it might
have appeared occasionally to shift its position to some extent,
but, as far as I could judge during an hour's observations, this
was not really the case, flickerings at times covered portions of
it, and at other times the whole became faintly luminous; but
by marking its position with reference to some small stars, this
seemed to me to be unaltered. Most singular were the termi-
nations of the streamers they culminated at this circle, not bing
undefined or gradually evanescent, but having angular tips far
brighter than the portions immediately beneath, the nearcst
illustration to which I can give is an inverted fish-tail or bats-
wing gas burner, except that this gives a feeble light at the
point, while the aurora tips were whitest and brightest there,
the streamers now fading off and now  becoming brighter and
tinged with red as they got to 400 or 500 from the horizon; the tips
varied constantly, but preserved the mean distance from the pole
or focus of the aurora. The position of this was, as far as I
could ascertain without star maps or instruments for observation,
about i ' W.N.W. of Vega.    The convergence of the beams
was not in appearance conical, but dome or cupola shaped; this
was, however, in all probability an optical illusion. Whetha