OF ed, 22, 1883] 
as the year draws to its close we find ourselves surrounded 
by a swarm of calendars; the insurance-office, the 
journalist, the general-storekeeper, the stationer, the 
watchmaker, the grocer, all vie in pressing on our accept- 
ance something to remind us how time flies ; often padded 
with most irrelevant pieces of innovation, but sometimes, 
it must be owned, got up ina very attractive form. We 
do not quite see how all this can be made to pay. We 
should have thought it a very expensive and often un- 
called-for mode of advertising. But that is no affair of 
ours. Living in “a nation of shopkeepers,’ whatever may 
be our private impressions, we are bound to believe that 
't isfound a remunerative mode of expressing gratitude, or 
Jnxiety, as the case may be. But whatever may be the 
donor's purpose it is not quite easy to see what corre- 
sponding purpose is, generally speaking, to be answered 
on the part of the receiver: for, with certain exceptions, 
it really signifies very little to the bulk of the community, 
how the fifty-two ensuing weeks are arranged. One great 
exception of course is the festival of Easter, and the 
others that depend upon it. But as to these there is 
always a sufficient general understanding, as there was in 
our least educated days, when there were comparatively 
few that knew how to use a calendar: and as to the 
phases of the moon, the only other leading feature in 
ordinary almanacs, their notification is rather convenient 
than necessary, excepting for those who believe, as old- 
fashioned people still do, with Prince Bismarck at their 
head, that the moon has an influence distinct from its 
attractive power. But, say what we will against the 
necessity of a general diffusion of almanacs, public feeling 
is on the other side, and even those who could do very 
well without these favourite articles, and seldom refer to 
them, would not feel satisfied if they did not possess 
them. 
One curious feature in the case, however, is that so few 
comparatively have any correct idea of the principles on 
which almanac-making proceeds. We suspect that even 
among such as pass for educated people it would be easy 
to find those who would not be very comfortable if they 
were required to explain the want of correspondence 
between the reckoning by weeks and that by months, the 
unequal length of the latter, the necessity of intercalation 
or the cause of the difference between the “styles "—im- 
portant as that was thought in its day, even to the excite- 
ment of popular indignation. As to such matters, if it is 
true that “we take no note of time but by its loss,” it is 
nearly as true of a large portion of even civilised society, 
that they take no note of the arrangement of time—except 
perhaps by misunderstanding it. However, there is no 
excuse for such ignorance (if we may be forgiven the ex- 
pression) for the future, if people will take the trouble of 
referring to the little work whose title we have quoted 
above. It will not indeed enlighten us much as to the 
root of all the difficulties—the incommensurable durations 
of the day and month and year, or help us to make out 
the strange old machinery of cycles and epacts and 
golden numbers by which the calendar was kept right, 
but it will do what is practically of much more value, set 
before us something of the processes, and all needful 
results, of the most accurate computations. 
The title was a puzzle to us at first, for we had been for 
so many years acquainted with a very unpretending 
NATURE 
387 
though most useful Churchman’s Almanac, that we did 
not comprehend how it should now find its place in 
NATURE, till we remarked the continuation of the title ; 
this, promising perennial instead of annual information, 
at once made a claim to attention which we find is well 
deserved. There are a good many curious and out-of-the 
way pieces of information in the three pages of introduc- 
tion—among which we may mention the explanation of 
the reason, hitherto to us so incomprehensible, why the 
accounts of the public revenue are made up to the odd- 
looking epoch of April 5—and this is followed by a per- 
petual calendar, as far as Sundays are concerned, to a 
period that the youngest now living will never see; while, 
for historical purposes, the retrospective portion is an~ 
authentic and valuable resource as to many indefinite 
matters in chronology, the correct determination of which, 
as antiquaries well know, often involves considerable 
trouble. The author has fulfilled his undertaking, as far 
as we can judge, with especial care and attention ; and if 
his work, which is one of the thinnest of folios, is so far 
less in accordance with the ideas of this ‘‘ handy-book”- 
loving age, we must bear in mind that the form was im- 
posed by the extent of its tabular matter, and that though 
there is little to attract in its formidable array of figures, 
its intrinsic value is, for those who need such aid, of a 
high and enduring character. 
LETTERS TO THE EDITOR 
[Zhe Editor does not hold himself responsible for opinions expressed 
by his correspondents. Neither can he undertake to return, 
or to correspond with the writers of, rejected manuscripts, 
No notice is taken of anonymous communications. 
[The Editor urgently requests correspondents to keep their letlers 
as short as possible. The pressure on his space ts so great 
that it ts impossible otherwise to insure the appearance even 
of communications containing interesting and novel facts. | 
Hovering of Birds 
Mr. Airy asks for a diagram explaining my views as to the 
hovering of the kestrel and of other birds, asserting at the same 
time that these views would establish a ‘‘ miracle.” 
If Mr. Airy will be so good as to look at the beautiful drawing 
of a kestrel in the act of hovering, by Mr. W. Wolf, at p. 160 of 
the ‘* Reign of Law,” he will see an illustration far better than 
any diagram. Mr, Wolf is an excellent naturalist as well as an 
accomplished artist, and his drawing of the kestrel was made to 
represent his own knowledge and observation of the act of 
hovering, and not to set off any theory of mine. 
It will be seen that the body of the bird is represented as at a 
considerable angle to the horizon, and (of course) to any hori- 
zontal current of wind. 
It is by placing itself in this position to the wind, and by a 
wing-action accurately proportioned to the strength of the 
breeze, that the bird accumplishes the feat of hovering—which 
is no miracle, but the mechanical result of the ‘‘ resolution of 
forces.” 
The hovering of a boy’s kite is a miracle of the same kind. 
The element of weight is here represented by the string, held at 
the surface of the ground, 
Mr. Airy is, however, mistaken in his description of the facts. 
He speaks of hovering being performed with ‘‘ wings motion- 
less, not fluttering.” Now I have never seen a kestrel’s wings 
motionless when hovering. Always when the air is still, and 
always when the breeze is only moderate, the wings have a rapid 
and tremulous action, varying from moment to moment according 
as the ‘‘ muscular sense”’ directs it, and feels it to be needed for 
the ‘‘ poise.” But sometimes when the breeze is very stiff this 
action may be suspended for a moment or two, I have seen this 
Occasionally. But even in this case I could detect the quivering 
of the quills. 
The sea-swallows perform the evolution perpetually over the 
water when it is as still asa millpond, In all cases the inclined 
