NOTES, QUERIES, AND REPLIES.

THE

ENGLISH MECHANIC

AND MIRROR OF SCIENCE AND ART.

AS

MECHANIC AND MIRROR OF SCIENCE appears this week in an enlarged size and an altered form. In putting the advertisement pages outside, we have acted in obedience to a generally expressed wish on the part of our subscribers. No doubt the publication will be subject to some disadvantages from this change, as it will be less exhibited in shop windows, and will therefore be less under the eye of the passing public. On the other hand, our subscribers, as we intimated last week, will derive decided advantages from the alteration, and they may easily make up for any disadvantage we may suffer by introducing the work to an enlarged circle of readers.

OURSELVES AND OUR SUBSCRIBERS. ENGLISH MECHANIC is therefore a reflex of the creature asked us, of all things in the world, to promised last week, the ENGLISH intelligence and the generosity of thousands buy a brick, showing us at the same time a of subscribers. Its contributors are numbered small engraving of a brick on a card. We asked not by units, as in most publications, but actually her what she meant, and she said they were by thousands. Each one contributes according to about to build in some part of the north of Engthe wealth of his intelligence, or his desire to im- land a temperance hall, and that it was comAny one who has listened to puted that each brick in the building, and the part it to others. debates in mutual improvement societies, at an labour of putting it there, would cost about a educational or scientific conference, or in Parlia- penny, and she wanted us to assist to build the ment, knows the standard of eloquence varies with hall to the extent of a single brick. Did she the speaker. Some speak well, and to the point, and possess fewer charms, and speak less musically, we should have bought a brick. As it was, others occupy time to very little purpose; say what others have said before them, and in a less effective though pennies were of some importance to us It is then, we bought more than one, and have the way, or say things that are erroneous. pretty much the same in our ENGLISH MECHANIC's satisfaction at this moment of remembering that national improvement society. Some correwe assisted in a very small way in raising a temWe have increased the size of the paper because spondents write about what they thoroughly un- perance hall. So it is with the contributors to we desire to satisfy the largest number of sub-derstand in appropriate language; others are less the ENGLISH MECHANIC. Each one, by replying scribers. Some may say, Why not increase fortunate. They either ask questions which others to a single query asked by a brother reader, conthe number of pages, instead of increasing the have asked before, or go over ground which tributes his brick to the Temple of Knowledge. size of the pages? Our answer is, Because others have trodden with more effect. But increasing the number of pages involves the woe betide them if they make mistak es. necessity of double machine labour, and con- Then a half a dozen are ready with pen and ink, sequently double expense. When we have from not, as they say in the House of Commons, to time to time given a Supplement of Eight catch the Speaker's eye, but to seize the Editor's Pages, it has cost us nearly as much for attention, in order to correct the mistake,and rebuke, machine work—that is, for working off the sheets not always in the most parliamentary language, from the type, as we have paid for machining the the offender. Sometimes a comparatively puerile ordinary impression of thirty-two pages; or, in question evokes an elaborate reply, or an incorother words, it costs as much to work off a small rect answer leads to an interesting controversy. sheet as a large one. As it became necessary to This picturesque variety constitutes the chief give additional space, it was also necessary that charm of the ENGLISH MECHANIC. In the House the size of the page should be increased. of Commons, any member has the right to ventilate his own opinions on any special subject, and BY A FELLOW OF THE ROYAL ASTRONOMICAL we have frequently been surprised to see a poor SOCIETY. speaker on his legs "in that oldest temple of (Concluded from page 649, Vol. X.)

During the past fortnight we have received, in response to our invitation, many suggestions for the improvement of Our Journal, with some of

Our readers will be glad to know that for some time past the ENGLISH MECHANIC has been increasing its circulation and its influence week by week. It circulates at the present time not only more than any scientific publication in this country, but more than all of them put together. This is authoritatively stated. It is right that our cerrespondents should know to what a large number of readers they speak, and that our advertisers should also know to what a large constituency they appeal.

TIME.

which we shall comply. More than one has suggested that the contents of each number be manner to almost empty benches. Take away placed on the outside page. This we have done. his right to do so, and you immediately vitally by this time prepared to learn, is to observe the self, the use of which, as the reader will be As it may be expected, different readers and impair the value of the house as a consultative sage of Celestial objects over the Meridian, either for pascorrespondents are desirous that their favourite and representative assembly. As in the House of obtaining the time or determining what is called subjects should receive more especial treatment. Commons so in the ENGLISH MECHANIC. Some-Right Ascension. The way in which observations If we complied with such requests we should favour times, it may be, a somewhat illiterate man asks are actually made is this. Just before the exsome at the expense of others, and so to some what may be supposed by many readers an un-pected time of transit of any given star, the teleextent prevent the primary object we have in view important question. But it is not unimportant scope is elevated, by means of its altitude circle -that of providing the largest amount of useful to the asker, and possibly to thousands of others and level, to the height proper for its perception. information for the largest number of readers. similarly situated. If, then, the well-informed Now what the observer has to do is to note with It should, however, be borne in mind that will be tolerant of the ignorance of their brother all imaginable accuracy the instant of the star's the ENGLISH MECHANIC is to a large readers, sympathise with them, and do their best passage over each of the wires, and this he does extent what its correspondents make it. Its to enlighten them, the fundamental purpose of by listening to the beats of the clock whil subscribers may be considered as members this journal, under, its present management, will regarding the star, and we now see the impor of a vast mutual improvement society, who consider it a duty or tance of the clock having a clear sharp tich. a privilege to instruct As it will very rarely happen that the star each other. One person asks for information on beat, we have to estimate the fraction of son Lad. exactly on a wire at the exact instant of the icck's some particular subject, and another person, This is done by comparing its distance several hundred miles away, it may be, sends it, wire at the beat before it crosse not only without fee or hope of reward, but at his Several years since, when passing through the distance at the beat after it crosses it. Reference own expense. He, however, has the satisfaction streets of Liverpool, we were accosted by a pretty to Fig. 6 will explain this. of knowing that his letter, suggestion, or recipe | little girl. We shall never forget her bright stars Remembering that as the tele copa ing may be of benefit to thousands besides the one blue eyes, and her hair, which fell like woven sun-right-hand side, and to leave it on the l seem to come into the who specially asks for the information. The beams over her shoulders. This pretty little if we imagine that, in the Zure, a

freedom in the world's spending inke way WE must, however, return to the Transit it

be answered. Every correspondent may con-
tribute something to the common stock for the
common good, and by so doing he will in no way
impoverish himself, but do something towards
enriching all.

m the

it, with tha

involving the union and

having entered at the righthand side is at a at the 17th second of any given minute, and at bat the 18th, then we should estimate that it was on the wire itself at 17.88. Or, again, if it were at at 52, and at d at 53, we should put down its timeof crossing the wire as 52 58., and evidently the higher the power employed, the more rapid will be the apparent motion of the star, and the more accurate these subdivisions. The object of observing stars between the two horizontal wires couple of examples-and, first, At what hour will he called attention was that combustion took

is that all transits should be taken over the same parts of the vertical ones. Supposing, then, that the hour, minutes, seconds, and fraction of a second at which one star was upon each of the five wires is noted, all we shall have to do is to add the five observations together and divide the result by 5 to obtain the instant of the star's passage over the central wire, which, if the instrument be in adjustment, will coincide with the meridian. In the case of the Sun, Moon, and Planets, which present sensible discs, as of course it is the passage of their centres over the Meridian which is the phenomenon to be observed, the mode adopted being to take the time of passage of the west or preceding limb over all the wires, and then to do the same with the east or following limb, the mean of these two sets of observations being evidently the instant of the transit of the centre or the body we are observing. The “Nautical Almanac" gives the Right Ascension (or distance in sidereal time eastwards of the Vernal Equinox or first point of Aries) of 148 standard stars, as well as that of all the members of the Solar System; so that, as our Sidereal Clock marks, or should mark, Sidereal Noon, or Oh. Om. Os. when this first point of Aries is on the Meridian, we have only to compare the observed time of passage of any given Star, &c., with its Right, Ascension, as given in the "Nautical Almanac,' to find out the Error of the Clock. It will further be instantly seen that a comparison of the Clock Errors day after day will give us the Clock Rate. An actual example of a transit, taken at random from our Transit book, under the date of the 9th of October, 1869, will exemplify a good deal that we have been saying:

44.3
10.2
36.1

Meridian. Turning this into Solar time by the chemical action
aid of the table on pp. 506 and 507 of the material alteration of two substances with
which a good clock, regulated by Mean Solar and in the production of light; was a cause of
"Nautical Almanac," we shall have the instant which we were familiar in the use of fuel
time, should indicate when our star is on the
middle wire of the Transit. Supposing that our oxidation, the one material being yielded by fuel
reader has the "Nautical Almanac" for this and oil of tallow, and the other being furnished
The second point to which
year before him, we will illustrate this rule by a by the atmosphere.
n Ursa Majoris South on the night of the 12th of
March at Greenwich? We find on p. II. of the
month of March, that
selected the Sidereal time at Mean Noon is
on the day we have
23h. 19m. 43 288. Turning, now, to p. 364, we
at the same date is 13h. 42m. 26 04s. Adding,
see that the Right Ascension of n Ursa Majoris
according to the precept, 24 hours to this, we
get 37h. 42m. 26 04s. Then subtracting from
this the Sidereal time at Mean Noon-thus:

we finally obtain 14h. 20m. 21-4252s. as the
mean time of transit of the Star referred to, or
the instant which a good ordinary clock ought to
indicate as n Urs crosses the middle wire. This
will be seen to be 2h. 20m. 21-4s. after midnight
on the 12th of March. Or, again, What will be
the mean time of transit of Sirius on the 11th of
April? From the Right Ascension of Sirius,
6h. 39m. 24 82s., we take the Sidereal time at
S. Mean Noon, 1h. 17m. 59 85s. ; we get 5h. 21m.
24-978. Converting this as before into Mean time
we obtain 5h. 20m. 32:31s. as the instant by a
20 good ordinary clock or watch that Sirius will be
on the Meridian. We may obtain the clock rate
without any reduction of the observation,
if we bear in mind that any given star ought to
return to the Meridion after an interval of
23h. 56m. 4-09s., as shown by a clock or watch
We believe
indicating ordinary or Mean time.
there is a little book just pub ished called "How
to keep the Clock Right," the author of which
we fancy must proceed upon this principle of ob-
serving this interval of 23h. 56m. 4 098. between
the successive returns of any particular star to
some fixed point in the Heavens; but we have

27.9

120.5

.2

20 37 36 10
20 36 59 72

+36.38

It will be noticed that instead of adding up the whole of the five observations, and dividing the result by 5, we have merely added the seconds 2

together and multiplied the result by 2;

1

10

thing being obviously of it. The only precau

5

tion necessary is to add or subtract as many fifths of a minute, or 12 seconds, as shall make the result correspond with the number of seconds shown at the middle wire; because in reducing a really good observation, the decimals of second are all that we need take account of.

never seen it.

Into the adjustment of the Transit and the of any corrections to be applied to its indications, we shall not here enter. Should the want of information on these points be felt, and the desire for it be expressed, we might at some future time perhaps, enter fully into detail on this subject. As it is, we feel that in giving directions for making these adjustments and corrections, we should be addressing a very limited public indeed, and occupying precious space, which we have already considerably trenched upon. Our present, and we would fain hope not wholly unsuccessful, endeavour has been present in a simple form an e position of the mode in which the succession xf natural phenomena is made subservient to the purpose of the equable subdivision of Time; and so, more by the method of illustration than in a merely didactic way, to remove some of the vagueness which attaches to popular conceptions on this subject.

It may however, have occurred to any one who has carefully followed us so far, suppose that we do get the exact error and rate of a Clock, as far as Sidereal time is concerned, what use can we ake of this when we have got it? Well, Mean Selar time can, by an easy process, be derived immediately from Sidereal; but perhaps the simplest way for a beginner is to compute the mean time of Southing of the object he proposes to observe; be can then compare its transit directly with nary Clock. This is most simply effected by

place in several different forms; tha: there were
several conditions essential for active combustion
effects of combustion were the evolution of heat
or burning; that two of the most prominent
and light, and then there was between all the
relation which was constant and uniform-that
phenomena attending combustion, a quantitative
is, the relations between the quantities of two
materials uniting in such a way as to constitute
combustion, and
the quantity between the
materials uniting and effects produced, either the
amount of heat generated by their union or be-
tween the quantities uniting, and some effect due
to the heat produced by them. Lastly, he pointed
out that there was a difference between the
in matter.
temperature and the quantity of heat contained

The

By

on Monday, the 13th inst., is as follows:-" Use
The precise title of the second lecture, delivered
of fuel for domestic purposes, as a source of
motive power, for industrial operations not re-
quiring intense heat, distillation, evaporation, &c.,
and for producing cold; varieties of fuel." The
time at the disposal of the lecturer did not allow
of his dwelling upon all these topics in detail,
but after some general remarks, he proceeded to
observe that temperature could only, in a certain
limited sense, be taken as measure of heat.
use of coal for domestic purposes had only be-
come general during the last hundred or hundred
and fifty years; and although the means of using
it were considerably improved, yet many of the
fire-places now in use were very defective, inas-
much as the greater part of the heat produced
from the fuel was wasted. In a mass of fuel in a
state of bright glow, the quantity of heat that was
radiated in the same manner that light was dif-
fused, varied from about a quarter to one-half of
the whole. In many fire-places, a great deal of
heat, instead of being radiated into the room, was
radiated up the chimney. Great economy, as far
as fuel was concerned, was effected by the use of
close stoves, which, on the Continent, especially in
Germany and France, was almost universal.
the use of these stoves, a small amount of fuel suf-
ficed to keep apartments warm. Similar stoves had
been introduced into this country by Dr. Arnott,
but had never found much favour with the English.
Although chimneys were universal here, they
were by no means so in all parts of Europe. In
certain parts of Italy and Greece but few of the
houses had chimneys, the only means of warming
rooms being by open braziers, like those used by
the ancient Greeks and Romans. This mode of
burning fuel was open to the serious objection
that the air became vitiated, owing to no mode
of escape being allowed to the carbonic acid gas.
After describing some of the more recent im-
provements made in fire-places, the lecturer
offered a few remarks upon the use of gas for do-
mestic purposes. The recommendations in favour
of gas were convenience, cleanliness, readiness for
use as well as for being lispensed with. Yet,
notwithstanding these recommendations, it must
be always regarded as a very dear kind of fuel
when compared with coal or any fuel of that
nature. Speaking next of fuel as a source of mo-
tive power, the lecturer remarked that this was
undoubtedly one of the most important of all the
uses to which fuel could be put. Its use in this
respect was based upon the principle that heat
being itself a condition of energy was capable of
being converted into mechanical force. It was
chiefly through the medium of water transformed
into vapour that this motive power was produced.
In this case, the heat generated by combustion
was expended in vapourising the water, and in such
cases there was a d finite relationship between
the quantities of heat expended and of water

the following rule. From the Right Ascension of the ON THE PHENOMENA OF COMBUSTION. Vapourised. Every pound of boiling water re

lanet, as the case may be (adding, if

nery, 24 hours), subtract the Right Ascen

of the Sun at the previous Mean Noon,

given in the "Nautical Almanac" at p. II. of Ο

SPECIAL REPORT.

N Monday evening, March 6, in the Lecture onth under the head of" Sidereal Time at Theatre of the Society of Arts, the first Noon." The remainder will be the Side- of a series of four Cantor Lectures on Combustion 1 hours, minutes, and seconds after Mean Noon was delivered by Dr. Benjamin Paul, F.C.S. it which the body in question will cross the He first showed that combustion was generally a

quired 966 units of heat for converting it into steam, or just five and a third times as much heat as was requisite to raise the temperature of a pound of water from the freezing to the boiling point. The lecturer then alluded to the relation ship between heat and mechanical energy, and in doing so briefly traced the history of the mechani cal development of heat from the production of