is quite justified in taking it to be an indi cation that such a work was wanted. To still further enhance the value and extend the usefulness of the book the author has carefully revised the old matter, cutting out all that was doubtful or obsolete, and elucidating any points not previously clear. The information concerning sewerage works has been brought up to date; all useful inventions relating to the construction of sewers and drains are described, and the tables which formed so important a feature of the first edition have been amplified and increased in number. The work is already recognised as a text-book, and has attracted the attention of sanitary engineers on the Continent, where works of the kind described have at last begun to receive the attention they deserve.

wall which would be found to reach from adapted to their particular need." The demanded within five years, and Mr. Latham London to Rome. Nay, the coal brought drawings are so far complete that they supply last year into the London district alone a characteristic example for all the cabinet would have formed a similar wall, extending work in a house, and in the hands of a from London to Brighton! As a final skilful workman may become useful by sugpiece of statistical information our author gesting the thing that is really wanted. The calculates the amount of coal raised since amount of information given is, however, the beginning of the present century in very unequal: for while full directions are the British Islands, and gives it as furnished for making a kitchen chair, the 3,566,000,000 of tons-a quantity which, cabinet-maker is left to his own devices in piled up 74ft. high, would cover the space copying the design for a wardrobe. Some bounded by Brixton-hill on the south, of the designs are good, but others are very Upper Holloway on the north, Hammer- bad, and when the author leaves his own smith on the west, and the West India line he falls into the usual blunders. To Docks on the east (an area of about 50 render the work complete a piano-case was square miles)! necessary, and accordingly we have one which would give even Rubinstein the fidgets; but as there is not much opportunity for design about a harmonium, the author sets out to describe the interior as well, and his statements will serve to amuse the "practical cabinet-maker" who is also acquainted with the internal economy of the instrument. "In order to make a good and faithful working drawing," says the author, "it is absolutely necessary that the draughtsman should be acquainted not only with the practical part of the work, but that he should be also thorougly posted in the details of the various styles"- -a sentiment with which his readers will heartily agree.

At so prodigious a rate of consumption the serious question arises as to how long our known supply of coal may be expected to last? The decision to which Mr. Wiltshire comes is that, if we excavate to a depth of 4,000ft., we have enough-at the present rate of demand-to last us for 1,000 years. On the other hand, if we confine our operations to a depth of 3,000ft., then will another 300 years find us at the end of our stock of mineral fuel. It may, however, well be questioned whether some branches of industry, involving a large consumption of coal, are not on the eve of departure from England; and it is yet far too early to speculate upon the effect which the electric light will have upon the employment of coal for gas-lighting. At any rate, we have the selfish consolation of knowing that our ascertained supply" will last our time."

4 Glossary of Biological. Anatomical and
Physiological Terms. By THOMAS DUN-
MAN. London: Griffith and Farran.
MR. DUNMAN is correct in his belief that a
glossary of the terms used in biology,
anatomy, and physiology, is wanted by
students of those sciences, and his attempt
to supply the want will be appreciated. Mr.
Dunman prints the Greek roots in English
characters, "choosing rather to run the
risk of offending the susceptibilities of the
classical scholar than to endanger the per-
fect clearness of the work to those to whom
the Greek characters are not familiar." In
our opinion it would have been advisable to
omit them altogether, for what use is the
Greek word in italic to the student who
cannot find time to learn the Greek alpha-
bet? The indication that the word was
derived from the Greek with the meaning
of the root would have been sufficient. As
it is, the conversion of the characters will
often puzzle the student who is inclined to
look up the words in the Greek lexicon, for
Mr. Dunman says that branchia is Greek
for gill, and writes chylos and chumos,
sympleko and sunkope-little refinements
which will help only to confuse the student
unacquainted with Greek, especially as he
will also find numphe and mule, with
Cypselus entered as Greek. These, how
ever, are minor defects, the definitions
being, as a rule, correct, though in some
cases the roots given are not strictly ac-
curate. There are many terms in use, too,
which are compounded of Greek words
already applied to designate certain objects
or functions in these cases the compound
word has more direct reference to those
objects or functions, and consequently the
too literal translation of the Greek roots is
anything but an explanation to the student.
In a second edition, which will, we think, be
surely asked for, these blemishes may be
easily corrected, and we think it would be
advisable to adopt the Greek characters, or
else to omit their English representatives.

To any one in search of a mass of curious and recondite information upon a very familiar subject, we could hardly recommend a cheaper or more compact source than Professor Wiltshire's excellent little pamphlet. It contains the pith of numerous costly and inacessible works, and is thoroughly readable from cover to cover. Our Old Nobility. By "NOBLESSE OBLIGE." London: The Political Tract Society, 31, Tavistock-street, Covent Garden, W.C. THIS volume is a reprint (with corrections and additions) of a very interesting series of articles which have recently appeared in the Echo newspaper. Just now, when peers, like all other personages and institutions, have to stand or fall in public estimation by their own merits, and cannot afford any longer to depend on the proverbial English"love for a lord," this well-written history of the antecedents, origins, and acquisitions of the different members of the British nobility cannot fail to interest every Englishman. The information it contains will prove especially useful to students of the land question. Those who have read the articles as they appeared in the Echo will, we are sure, be glad to secure them in a more lasting form, and the low price of the volume-half-a-crown-should insure for it a wide general circulation. The Practical Cabinet-maker. By A WORKING MAN. London: Wyman and Sons. THIS book is made up of a collection of working drawings with explanatory notes, and we are assured on the title-page that they are by a working man." If it had not been for that assurance we might have ventured to doubt whether any one accustomed to the use of tools had compiled this work; but as it is we can only express the opinion that the "working man" has mistaken his vocation. It may be true, as the author says, that there is apparently an absence of any desire on the part of our workmen to dig for and search after that knowledge which applies to their work, or THE second edition of Mr. Latham's text to engraft and cultivate in their minds the book of sanitary engineering has been conprinciples of art and design; but if so, it siderably enlarged, no fewer than 200 pages was surely the business of the "Working having been added. It must be gratifying Man" to endeavour to teach them, es- to all sanitarians to find that the work has pecially as he appears to think "there are been so widely appreciated that a second no really good books on this subject' edition of a purely technical work has been

66

:

Sanitary Engineering. By BALDWIN
LATHAM, M.I.C.E. London: E. and F.
N. Spon.

Annual Report of the Board of Regents of the
Smithsonian Institute, 1877. Washington:
The Smithsonian Institute.

THE report of the Smithsonian Institution
for the year 1877 has an especial interest
from the number of original communica
tions appended to it. The report proper is
the usual formal record of the work done
by the Institution, which has a melancholy
interest as the last that can be penned by
the late secretary, Joseph Henry. The
general appendix contains a translation of
Holmgren's paper on "Colour Blindness in
its Relation to Accidents by Rail and Sea,"
with a short communication on the same
phenomena, written by Joseph Henry in
1845. Three reports of the Geneva Society
of Physics and Natural History, by Plan-
tamour, Müller, and Adolf Favre respect-
ively, occupy a few pages with appropriate
matter, and the rest of the volume is
occupied with papers having a special
interest for Americans, such as the collec-
tion of short memoirs on meteorological
subjects-a branch of science that of late
years has attracted much attention in the
United States. The ethnological papers
are, however, of most interest, the con-
tinued researches made in Wisconsin,
Colorado, Illinois. Pennsylvania, and Florida,
disclosing a rich field for writers on pre-
historic races. Some of the more interesting
mounds are those which take the forms of
men, birds, and animals on plaħ. A few of
these are illustrated with measurements
marked, but unfortunately, owing to the
untimely death of the geologist, we have
only the commencement of his paper and
the brief notes found in his field-book.
These relics of an early race of North-
American people disclose the fact that the
Red Indian was not the original lord of the
forests and prairies from which he has been
driven by the white man; but the facts at
present gathered are too disjointed to
enable us to form a picture of the ancient
scenery of North America.
Just as
palæontologists and geologists have been
encouraged to search, so we may hope that
the ethnologists will pursue their labours
until further knowledge of the mound-
builders is obtained. Such discoveries as
have already been made are noted in the
volumes issued by the Smithsonian Institu-
tion.

Elementary Geometry, by J. W. Wilson, M.A. (Macmillans), is the fourth edition of a school-book which has been received with considerable favour. It contains the subjects of Euclid's first six books.-Metals and their Chief Industrial Applications, by C. R. Alder Wright, D.Sc., is the substance of a course of lectures delivered at the Royal Institution, with experiments. In book form they may be of use as a class reader or as lecture notes, but in several cases the author has omitted to mention the "chief industrial uses" of the metal he briefly describes.-Practical Physics, by F.

distinctive and correct as is possible; additional Pieces will not be often enough required to render necessary the finding of special terms for them.

Guthrie, Ph.D., is another of the London there placed beneath the Passage-Board, between the different Parts will, I think, be found as Science Class books issued by Messrs. the two Manual Sections; thus not only devoid Longmans, and edited by Prof. G. Carey of being of any use (as the Passage-Board is Foster and Philip Magnus, B.Sc. It treats only required to bear the Tuner's weight), but of molecular physics, waves, and sound, and very much interfering with getting at the has an appendix containing many useful Pallets of either Great or Swell. y. The foregoing will, if carefully followed, In addition to this the Frame is of Oak-well carry the Builder up to a considerable size hints on the construction of apparatus. quite a piece of extravagance anywhere, and of instrument: for larger Organs it is not necesThis series of class books is deserving of, here positively harmful, for the Fastenings- sary here to go into detail, for they will, as a and is meeting with, considerable favour. instead of being Nutted Bolts-are merely rule, be undertaken only by really experienced -The Silver Question Reviewed, by An large common Screws: thus not only is there Makers; and besides this, the smaller Designs Indian Official (Longmans) is another con- difficulty in getting shoulder-impact tight will easily lead up to the larger. It may, how tribution to the controversy by a gentleman enough for the maximum of rigidity, but the who evidently believes in his own opinions. acid in the wood may probably in a short time ever, be observed that in all setting out of -Notes on a Novel Form of Sun-dial, by E. render the Screws themselves utterly immov-supported must be first marked in on the draw. Building-Frames, the various portions to be C. Caldwell (Whiteley), is a little pamphlet able. Altogether this Building Frame fur-ing, and then the Framing filled in to them; describing the construction of a cruciform nishes an instructive instance of what ought to afterwards comes consideration as to what-if sun-dial, especially adapted for use in inter- be avoided. (See a good Construction by the any-alterations or simplifications can be made tropical climates. It is a cross set up on a same Maker, t. t., ante.) without injuring the positions of the Parts-to horizontal stand, and inclined at an angle be supported. It must also be reflected how by equal to the colatitude of the place where it any modification can a Rail, &c., be made to is used. It is cheap and accurate, and conserve two or more purposes; remembering sequently recommends itself to travellers always that the fewer separate pieces there are and others in countries where the sun is a in an Organ the better, as the inconvenience of more frequent visitor than here. the cumbrousness and size of the separate Parts will be much less, as a rule, than that of their numerousness; especially as all Building. Frames (except perhaps sometimes very small ones) must be constructed to admit of taking to pieces for convenience of transit.

THE ORGAN: A COMPREHENSIVE
TREATISE ON ITS MANUFACTURE,
PROCURAL, AND LODGMENT.*

BY JOHN WATSON WARMAN,
Associate of the College of Organists, London.
PART I GENERAL TREATMENT
MANUFACTURE.

w. With the introduction of a Third manual it is, however, often necessary to place the Swell over the Choir: nor is there any real objection, provided the ventilation be properly attended to, so that the temperature at the two levels is the same (see as just said). Still, there will be many Instruments in which the three Soundboards can be on one level, and in all such the foregoing type of Frame will still be the proper one.

When there are Four Manuals the CornerPosts must generally be rather larger, and continued up sufficiently high to carry the Upper Soundboards, just as the lower ones are borne; only that sometimes-owing to this IN Soundboard being shorter than the lower ones -two connecting Cross-Rails will be required to run beneath it, its ends not reaching the Main Side-Rails.

tt. In the very excellently designed Organ built by A. Gern for Col. Makins, of London, the Building-Frame was of very simple construc

tion.

It consisted merely of four Posts, placed at the corners of a parallelogram-the tops of each pair-nearest-each-other being connected by a Side-Rail, and (uniting these latter) a single Cross-Rail extending the (greater) length of the Parallelogram, and carrying the one (Double) Soundboard which served the two

Manual, Sections. The bottoms of the Posts were of course fitted into a complete Kerb or Ground-Frame; suitable Rails near the bottoms of Posts carried the Bellows Reservoir; the Touch-Roller-Boards were fitted to the Kerb; and the Keys were placed at side (that is, at narrower end of Building-Frame), and on a separate Framing or structure.

** GENERAL DIRECTIONS.

u. This example of a Building Frame is, as will have been seen, from a Two-Manual Instrument: it may be taken as a foundation for all ordinary-that is, unconfined-One and Two Manual Organs; for it is, except under peculiar circumstances, best to have both these Sections on one level-(See Depart. of GEN. ARE.)-or nearly so (at all events when no Choir or Solo is present).

Lu. When

w. w. When there are two Soundboards
below, and one above, the Back Main Posts
will rise exactly as with the four Soundboards
just mentioned: the treatment of the support
of the front portion of this upper Soundboard
will then depend on circumstances; if space be
limited it will be best to carry up the front
Posts, and place the side Horizontal, just as if
there were two Soundboards to rest on it. It is

true that the Horizontals will thus be longer
than required, but that will generally be more
than compensated by the avoidance of the
obstruction of a Post opposite the space between
Great and Swell: it must also be remembered
that a Passage Board across at front will be
very valuable for tuning large Pipes of Great.

** CHAMBER ORGAN TYPE.

* TYPE NORMAL.

z. It is now necessary to say a little on the design of Building-Frame for Chamber Organs where such is not supplied by the Case itself: and note. the Type now to be described must be considered the best in all cases (up to a certain size of Organ-say, 15 Sounding Stops) where the Builder is really restricted as to space; over that size no Organ ought ever to be so confined as to render the adoption of this present Type of Frame necessary.

It will be seen that throughout this entire Department the word Frame is often used to signify the complete Building-frame.

in having the Uprights flat instead of square on [44, a.] The modification consists simply section, and so arranging that they are furnished by Styles of large Frames; these latter being screwed together at the corners, so constituting the Building Frame. The Uprights will thus be angled-that is, two conjoined sides of a rectangular Tube, such form giving, as we have already seen (41, p), great strength with small expenditure of material. It is to be also remarked that the thickness of the Rails will be reduced as much as possible, this being compensated to some extent by giving them increased breadth. It will easily be seen how much is gained on plan by this form: the Bellows can occupy the entire inside of the Frame, and yet the Posts not project-on plan

w. w. w. The foregoing assumes that there is no Intermediary or Middle Post assisting to carry the lower Soundboards. When this Intermediary exists it will obviously be the most economical method to continue it up, so to support the front of the Upper Soundboard observe-this Middle Post must not be notched out at its side, so that the Rail which carries the lower Soundboards will enter it, for that would weaken it (Post); the latter must be beyond Frame, either inside or outside. either attached inside (or outside) the Rail, or Another minor advantage lies in the fact that it must be pierced with a Mortice, and the a Bearing-Spur for carrying Plinth (Organ being Rail passed clean through it. In the latter on Runners) can be inserted right through the case the Post must be of size and shape accord-flat Upright without materially weakening it; ingly say if the Rail be 2in. pricked, have the (see further in PACKINGS (47, f). Post 3in. x 4in., the Mortice of course on the broader face; this method will be found to weaken the Post less than any other.

through confinement with respect to height, or any other cause-it becomes desirable to have the Manual RollerBoard set flat-wise (see Depart. of TOUCHACTION), and it therefore comes in the way of placing a Main Cross-Rail at the point just laid down (see i., ante), effort should be made to x. Observe, however, that even when this posit latter where it will take the chief weight Middle or Intermediary Post does exist it will of the Pipes. One very good treatment will be not be advisable to carry it up if room be very to set it close against the rear or outside of the limited, unless such carrying up be necessary on Back or Cross-Piece (sometimes termed the account of the great weight of the upper SoundFind Far) of the Windchest (see Depart. of board; and this latter will be only likely in an NDCHEST), by which means it-the Rail-Organ sufficiently large to positively demand wil not extend much below the under-face of proper consideration and allowance in the ter, and head-room for the Flat-placed matter of room. der-Board be generally obtained.

X.X. It will be seen that the Pedale Organ Semember that in such treatment the has been hitherto left outside the Frame; and mannot pass through "Wind Bar," as this is simply because its Soundboards or Chests must not be cut in any way so as to will be (except sometimes in the largest Instrued; it will here, therefore, be always ments) either actually on the Base-line, or only rely or wholly resting on top edge of sufficiently above latter to leave room for order to rise as much above latter Action beneath; and in all such cases its to the vertical depth-total of the Supports will naturally be very simple. When, however, it is wished to carry the Pedale on the regular Building Frame it will be very easy to do so. All that is necessary is to place the Main Posts outside instead of inside the Pedale Organ, and increase them in strength and number as required.

the t furn

being

Building-Frame-by Gern-of
mes's, Norlands, London, is
of the foregoing not
A Cross-Rail is

ew.

rved.

I will just add that the names here used for

b. The exact form of Frame I have after a great deal of consideration fixed upon as-on the whole-the best is as follows:

c. The Structure will consist chiefly of thres separate complete Frames; one for the back, and one for each of the Sides; to these must be added the Middle-Rails and the Cross-Rails. It must be distinctly understood that by back is here meant the side opposite that at which Claviers are placed, and it is for the present assumed that the fronts of the Frame and of the Case will be coincident-in other words, that the Clavier will be at the chief Front or Façade of the Instrument.

We will imagine a Building-frame suitable for an Organ of Nine Sounding-Stops; Two Mans. and Ped. Such an Instrument may be considered a Normal one for Chamber use.

d. The BACK-FRAME will be formed of two Styles and two Rails; the Upper Rail being placed (as a rule) as high as it conveniently can without interfering with its fuaction of carrying the back ends of the two Midlle Rails, which themselves carry the Manuale: the Lower Rail should also be kept pretty well up, in case of any Action having to pass beneath; but its

function of carrying the rear end of the FootBlowing T-spindle or other portion of BlowingAction must not be interfered with.

e. Each SIDE-FRAME will have its Upper Rail set at the extreme top of the Styles-its top edge, in fact, continuing the top ends of latter: the Lower Rail will be at proper height for carrying the Bellows.

(To be continued.)

EDWARDS'S IMPROVEMENTS IN

POLISHING METAL.

THE use of emery for grinding and polishing purposes is rapidly extending, new appliances being frequently devised for assisting the workman in his labour. One of the most suggestive of these is the subject of a patent obtained by Mr. Archer Edwards, of Shoreditch, for an invention of novel apparatus by which sheets of cloth, paper, or other flexible material, coated with emery, glass, or other abrasive powder, may be readily applied to and stretched and fixed upon bars, handles, or other supports, so that the abrasive material can be readily applied to the surface to be

and hinged longitudinally along the periphery the transmitted sounds, whether articulate or
at the end of one diameter. In circumstances otherwise.
where it is desired that a flexible cord or band Fig. 1 shows partly in sectional elevation
should be used for the purpose of grinding or the arrangement of apparatus employed for
polishing curved or flat surfaces, the patentee transmitting musical and other sounds accord-
prepares an endless band or cord of hemp, ing to this invention. A represents the ordi-
leather, or other sufficiently flexible and strong nary Hughes microphone, connected by means
material, but preferably of indiarubber, sur- of insulated wires with the reel on the pola-
rounded by one or more layers or covers of rised relay, B, a battery being placed in the
canvas, and covers this cord by winding circuit. The relay consists of a horse-shoe
helically round it one or more strips of cloth, magnet to one pole of which one end of an
paper, or other flexible material, coated or elastic steel armature is attached by a clamp-
covered with emery, glass, or other abrasive ing screw, the other end being free to vibrate
powder. The ends of these helically-arranged in front of the other pole of the magnet.
strips are attached to the cord or band by Around this pole is the coil of insulated wire,
cement or other convenient means, and the which forms part of the electric circuit. When
endless cord or band thus prepared is stretched a sound is delivered into the microphone the
round two or more drums or pulleys, which can pivoted tube or its equivalent, which forms the
be made to revolve at a sufficient speed by electric connection between the wires through
steam or other power. The articles to be the carbon block, will be thrown into vibration,
ground or polished are pressed against the and the even flow of the electric current being
moving cord or band as required.
thereby disturbed, the elastic armature of the
relay will be caused to vibrate in unison, as is
well understood, thereby reproducing at a
distance the sound received into the micro-
phone, A. In order to increase the volume of
the sound produced in the relay, the vibrating
armature is connected with a sound-amplifier,

PREECE'S IMPROVEMENTS IN
TELEPHONES.

HE following description of Mr. Preece's

treated in the same way and for the same improvements in telephones will be read D, by means of a wire. This sound-amplifier

purpose as metal files are ordinarily used.

The patentee takes two longitudinal bars or strips of wood, metal, or other suitable material, each of any required shape in transverse section to suit the particular purpose for which it is to be used, but having one of its surfaces flat or nearly so. These two bars are connected together by joints or hinges at one of their longitudinal edges, so that when the bars are folded together their two flat surfaces are in contact. Upon each of these flat surfaces are fixed one or more projecting pins, studs, or

with interest both in this country and America,
for reasons well known to our readers. The

FIG. 2

may consist of a piece of animal or vegetable parchment stretched over a conical tube, and

FIC.I

FIGI

pegs, preferably of metal, the projecting points or ends of which fit into corresponding holes in the opposite bar when the two bars are folded together. The emery cloth or other flexible abrasive material which is to be used is prepared in a piece of suitable size, and the bars hinged together as above described, being opened to a sufficient extent, one edge of the piece of emery cloth is fitted upon the projecting pins in one of the bars, and the piece is then bent round the outer edges and sides of the bars, and fixed upon the projecting pins in the opposite edge. The two bars are then forced together until the projecting pins in each bar pass through the emery cloth into the corresponding holes in the opposite bar, and by this means the emery cloth (or other flexible abrasive material) becomes stretched tightly and smoothly round the bars. The two bars thus closed may be held together by a hook, or catch, or other convenient means, or they may be used without further attachment.

A handle of convenient form may be formed upon or attached to one or both ends of one or both bars, and the entire apparatus, constructed and arranged as described, may be used as an ordinary metal file is used, for the purpose of grinding, abrading, or polishing metal or other surfaces. When the piece of emery cloth or other flexible material has become worn out, or it is required that it should be changed, it can be removed and a fresh piece substituted for it with great ease and quickness.

Fig. 1 represents the tool complete; Fig. 2 is an end view of the same opened, with the emery cloth placed round the bars; Fig. 3 shows the bars closed, and the emery cloth stretched tightly round them, but in this case of a different section. The invention may be applied to rollers or drums circular in transverse section,

www

invention relates to improvements in telephones | secured in place by a hoop, similar to a drum-
generally, but especially to those employed for head; or it may consist of a disc or plate of
the reproduction of musical sounds. An elec- ebonite or of thin sheet iron, secured in a frame
tric telephone is, as is well known, an instru- or open case. The wire will be attached to the
ment which causes matter at a distance to centre of the disc plate or parchment in any con-
vibrate in unison with other matter vibrating venient manner that will insure the transmission
at home. The latter, by its motion or vibra- through the wire of the vibrations of the arma-
tion, is made to form or to vary electric cur- ture to the disc plate or membrane. It will now
rents in such a way as to act electro-magneti- be understood that any sounds delivered into the
cally on the former, and reproduce in it similar transmitting instrument, A, will be reproduced
sonorous vibrations. In Riess's, Gray's, Var- in the receiving instrument, B, and the volume
ley's, Bell's, and other known forms of tele- of this received sound will be increased by the
phone, these sonorous vibrations are reproduced sound-amplifier, D; the increase of the volume
directly by the action of the electricity, and of the sound will vary according to the size of
are reinforced by simple sounding-boards or the disc or membrane put into vibration.
resonators. According to this invention the
vibrations produced in the receiving instru-
ment are transferred from their source to fixed
or stretched membranes or discs in such a way
as to increase the quantity of air thrown into
sonorous vibration. Any approved kind of
transmitter is applicable to this form of tele-
phone, but the patentee proposes in general to
use the instrument known as Hughes's micro-
phone.

The receiving instrument consists of a polarised relay, whose armature, vibrating in unison with the original source of sound, will, by its connection through a wire with a drumhead similar to that of the toy telephone, reproduce

Mr. Preece finds by experience that in transmitting sounds to one person a disc of about 2in. in diameter will produce a good result, but he proposes to increase the area of vibration relatively to the increased volume of sound required to be produced to suit various sizes of auditorium. He also proposes to connect with a vibrating armature two or more sound amplifiers of the proportion above indicated, so that the sounds transmitted from the Hughes or other instrument may be heard simultaneously by two or more persons. Fig. 2 illustrates this modification, where three soundamplifiers, D D D, are shown as connect d by wires or threads to the elastic vibrator.

(1.) The emissive power of bodies increases with the thickness of the radiating layer up to ON THE REPTILES OF THE PRIMARY a certain limit, then it decreases; hence there is for every substance a thickness of layer corresponding to the greatest emissive power, and which I have called "the layer of greatest emission."

CHAMBER ORGAN SPECIFICATIONS. Some prefer the oboe in the swell instead of I PURPOSE giving a few specifications of the gamba, but for an organ of this size a organs suitable for rooms of various sizes, gamba is sufficiently reedy and keeps in tune and designed principally to assist amateur so much better. organ-builders, who, often possessing the A large instrument may be agreeably to the mechanical ability to construct a creditable in- next specification; at the same time it is to be strument, are yet deficient in the technical remembered that increase of size now only knowledge requisite to design a pleasing-toned adds to the variety of tones produced, but does one. I do not intend at present to give any not give any greater facility for practice. to the making, for sufficient