Skip to main content

Full text of "The book of lantern ; being a practical guide to the working of the optical (or magic) lantern ; with full and precise directions for making and colouring lantern pictures"

See other formats







Ire without doubt the simplest in manipulation, 
the best in technical results, and therefore 

t ! he most papular Lantern Plates in the World. 

[r, E, H. JACQtJES, of Birmingham, carried off the First Prize 

against 250 Competitors last year in Transparencies 

on our Lantern Plates ! 

[r. PAUL LAME (Liverpool) writes us: 

'This year, as last, 1 find your LANTERN PLATES give 
:cellent results. I have just taken, the First Prize for Slides 
the Birkenhead Photo Society. My Work was on your Plates." 

i ' ' We cannot refrain from saying a word in praise of FRY'S 
fANTERN PLATES. We have just seen a batch of most beautiful 
Lides, made on these Plates by Mr. A. R. DEESSEE." 

PRICE is. per dozen, 

complete with Developer, Round Masks, Gummed Black 
Paper Edging, and Clear Glasses, 2s. per dozen. 

^ Fry's 2nd Grand Lantern Plate Competition, 1888-9. 



[amActonrg of flu " KINGSTON SPECIAL " Dry Plates, & 

5, Chandos St., Charing Cross, 


fakr: XiigttoMB-Ifcuiu. TelsgrajUc Adtes: "SnlMjements, London." 


A Lantern Slide, by the Author. 



Ppaetieal dr&icU: to t|?e: Wopking oj^ 
Optical (OP Magiej 

With full and precise directions for making and colouring Lantern 



(For many years Lecturer to the Royal Polytechnic Institution, 

London; Lecturer on Photography at the Birkbeck Institution; 

and Editor of "THE CAMERA.") 




Main L?b 





Chapter Page 

I. The Construction of the Lantern .... 1 
II. The Optical System of the Lantern ... 16 

III. Oxygen Gas Making 30 

IV. Limelight Jets, Kegulators, Pressure Boards, &c. . 50 

V. The Limelight and its Management . . .71 

VI Screens ........ 6 

VII. The Preparation of Lantern Slides, Diagrams, &c., 

without the aid of Photography . . . .97 

VIII. Lantern Slide Making by the Wet (Photographic) 

Process ^ . . 104 

IX. Lantern Slides on Dry Plates . . . .109 
X. Home-made Gelatine Plates 125 



XI. On Colouring Photographic Transparencies for 

Lantern Slides 145 

XII. The same subject continued 159 

XIII. Description of various Experiments Chemical, 
Electrical, &c. for Class Instruction, which are 
possible with the Lantern 171 

XIV. The Lantern as an Aid to the Photographer . . 204 

XV. The Art of Making Photo-Micrographs . .211 

XVI. Enlarging Photographs with the Lantern . 222 

XVII. The Lantern Microscope and the Opaque Lantern . 240 

XVIII. Various Lantern Accessories . . . 250 

XIX. Practical Hints to those who Employ the Lantern 
for Scientific Demonstration or for Entertain- 
ments in the Drawing- Koom or Lecture Hall . 2(54 


]S it is customary for an author to say a few 
words to his readers by way of introduction, 
before they become better acquainted with 
one another, let me briefly state the reason why 
this book is written, and why I felt some confidence 
in undertaking the work. The magic lantern has 
always been one of the most popular instruments 
ever made. So popular has it been, that children by 
the thousand recognise its charms, while many of more 
mature years have a secret hankering after it, which 
they would fain leave unacknowledged : " For it is but a 
toy," think they, " and we have left toyland behind 
us since we reached man's estate." Let me 
sympathise with these feelings, and own for my part 
a weakness for pantomimes and fireworks, which 
weakness I have occasionally the opportunity of 
indulging, on the plea of taking my children out for 
a treat. But let me say at once that the magic lantern 


is now no toy, but is recognised as a valuable aid to 
education far and wide. The reason for this is not 
far to seek. First, we have to look at the vast 
improvement in the instrument itself. So long as the 
greasy, evil-smelling oil lamp was almost the sole 
illuminant available, and roughly executed daubs in 
varnish colours on glass the only works of art (?) 
which could be purchased for the lantern, it did not much 
signify that the lenses were also of a faulty character, 
and no better in quality than the " bull's eye " of the 
nocturnal policeman. But when the brilliant limelight 
came to be adapted to the lantern, it was at once seen 
that the capabilities of the instrument were not only 
much increased, but almost without limit. It would 
be difficult to say offhand how many persons visited 
the Royal Polytechnic Institution in the forty years 
during which it was open to the public; but it is 
within my own experience that at one period, at the 
time of the ( ' ghost " illusion, they came at 
the rate of two thousand per diem. There is no 
doubt whatever that the Polytechnic caused this form 
of amusement to become popular, for the lecturers 
affiliated to the Institution travelled the country 
round, and gave similar entertainments in all parts. 

There are few branches of science in which the 
optical lantern cannot be made useful for purposes of 
demonstration, and as this fact becomes better known, 
every schoolroom in the kingdom will be provided 
with one. In every lecture theatre worthy of the 


name the instrument is already constantly called upon 
to illustrate various subjects, and I venture to state 
that its use will be greatly increased now that so 
much attention is being paid to the art of photo- 
micrography, by which enlarged pictures of micro- 
scopic objects can be easily rendered available for 
projection by means of the lantern. A large class 
of students can thus at the same moment study the 
structure of an organism which may be in reality 
invisible to unaided sight by reason of its minute 

But during the past few years, the number of those 
who interest themselves in the lantern and its 
capabilities has been vastly increased by the sudden 
popularity of the art of photography. Amateur 
photographers are now to be found in every town in 
the kingdom, and they are beginning to find out that 
there is no better method of showing their friends the 
pictures which they have taken than by means of the 
optical lantern. The same instrument, too, as it 
offers a means of making permanent enlarged copies 
of small photographs, serves with them a double 

The introduction as illuminants of the hydrocar- 
bons, under the name of petroleum, paraffin, kerosene, 
&c., has also had its share in the recent development 
of the optical lantern, for now a few pounds will 
purchase a better instrument than was procurable at 
any price twenty years ago. 

I . 


With these facts in view, I have long thought that 
a thorough guide to the working of the optical lantern, 
the preparation of its diagrams and pictures, the 
colouring of the same, the production of photo- 
micrographs, and everything pertaining to lantern 
work, would fill a vacant place in technical literature. 
Beyond the two or three shilling handbooks which 
have appeared, there is nothing of the kind procurable; 
and in the space available in such books, it is obvious 
that the various matters to which I have referred 
cannot be sufficiently dealt with. 

Some of the matter here printed has already 
appeared in The Amateur Photographer, and in The 
Camera. The author is indebted to the proprietors of 
both those periodicals for their courtesy in allowing 
both text and cuts to be reproduced in this work. 



November, 1888. 



that wonderful autobiography of Benvenuto 
Cellini, which Horace Walpole described as 
being " more amusing than any novel," we 
find the account of a weird incantation scene which 
took place in the Colosseum at Rome. Cellini tells us 
that he had made the acquaintance of a Sicilian priest 
who volunteered to initiate him into some of the 
secrets of necromancy. A meeting was appointed at the 
Colosseum, where " the priest, having arrayed himself in 
necromancer's robes, began to describe circles on the earth 
with the finest ceremonies that can be imagined. I must 
say that he made us bring precious perfumes and fire, and 
also drugs of fetid odour. When the preliminaries were 
completed, he made the entrance into the circle j and 
taking us by the hand, introduced us one by one inside it. 
Then he assigned our several functions : to the necromancer, 
his comrade, he gave the pentacle to hold ; the other two 
of us had to look after the fire and the perfumes ; and 
then he began his incantations. This lasted more than an 



hour and a half, when several legions appeared, and the 
Colosseum wa's^a'lk^all of devils." It has been suggested 
that these effects* w'er'e' produced by some form of lantern 
.das&ji^ ;imtag'6s[ oil .'the fcmoke from the burning drugs. 
Should this surmise be correct, it would refer the use of 
the instrument back to the early half of the sixteenth 
century Cellini having been born at Florence in the 
year 1500 and the event spoken of having occurred in 
his early manhood. 

But on careful perusal of the entire account of these 
supernatural wonders, I feel convinced that no kind of 
optical instrument can have been used. To produce any 
remarkable effect in such a large space as that covered by 
Vespasian's Amphitheatre would certainly tax the powers 
of the best modern lantern. Besides which, Cellini was 
a remarkably clever and observant man, and would 

FIG. 1. 

probably have detected the employment of any such 
apparatus. It is far more probable that the priest was 
aided by a number of confederates, and that these were in 


reality the legions of devils which so impressed the super- 
stitious mind of the Florentine goldsmith and sculptor. 
With far more reason might we suspect the use of the 
lantern in those manifestations which are said to take 
place among the so-called spiritualists and their mediums- 
of to-day. 

We are certainly on much firmer ground when we 
ascribe the first conception of the instrument to Athanasius 
Kircher, the learned Jesuit of the seventeenth century, 
who has left so many volumes to testify to the great gifts 
which he possessed. For in one of these books, Ars Magna 
Lucis et Umbrce, we not only find descriptions and dia- 
grams of numerous optical contrivances (I may note in 
passing that many of these drawings, redressed and 
elaborated, appear in modern text-books as new ideas), 
but several which show that Kircher quite understood the 
main principle upon which the optical lantern depends. 
A tracing of one of these rude cuts is given at fig. 1, 
from which it will be seen that the design to be projected 
by the lens is illuminated by three candles the brightest 
form of artificial light then known and an inverted 
image is thrown upon a screen at a distance. 

Here we have practically the germ of the aphengescope, 
or opaque form of lantern. But modern writers on the 
subject, in referring to Kircher, have curiously overlooked 
this most suggestive drawing, and have given another one 
from his book, which they erroneously describe as the first 1 
form of magic lantern. This I also reproduce (see fig. 2). 
The description appended to the cut certainly does not 
bear out that view, but points rather to a means of . in - 



creasing the light from any lantern by using a parabolic 
reflector behind the lamp or candle flame. The passage 
(translated) runs as follows : 

" To construct an ingenious lantern which may show 
things written at a great distance so that they can be 

" Let a lantern be made of the same cylindrical figure 

PIG. 2. 

as you see here represented, in whose base let a concave 
mirror be placed, having as parabolic a shape as is possible. 
Within the focus of this mirror let F, the flame of a 
candle, be fixed, and you will have "what is required, for 
it will shine with such unwonted splendour as to show by 
night, without any trouble, even the smallest letters when 
examined by the aid of a telescope. But persons looking 
at the flame from a distance will think that it is a great 
fire. If the inner sides of the cylinder are fashioned of 
polished tin in the form of an ellipse, they will increase 
the light. But the figure here given will sufficiently show 


the invention. E marks the handle and the opening (or 
window) ; C the chimney or fnnnel." 

It is worthy of note that Sir David Brewster, in his 
" Natural Magic," qnotes the incantation scene from 
Cellini at length, and states his conviction that the 
appearances were brought about by optical apparatus, 
although he admits that little was known of the action of 
mirrors and lenses nntil the time of Kircher. 

It is obvious, however, that such primitive instruments 
were of the crudest kind, and can only be regarded as 
interesting curiosities. Up to within quite recent times 
lanterns for projection held about the same relation to the 
modern instrument as does the bone needle of the cave 
men to the sewing machine. Like most instruments of 
precision, the optical lantern is the outcome of many years 
of patient thought and labour, and is the result of the 
working of many minds. No individual can be credited 
with its invention or discovery. The crude idea is, as we 
have seen, to be found in Kircher's book, and one improve- 
ment has been suggested here, and another there, until we 
have before us a very perfect optical appliance. 

The gradual advance in the instrument very naturally 
follows the introduction of improved illuminants for more 
general purposes. The oil lamp was superseded by the 
argand gas-burner, and this was in its turn supplanted by 
the whiter and better light afforded by mineral oil, while 
before this, for the better kind of lanterns, Lieutenant 
Drummond's brilliant limelight was quickly adopted as the 
best for the purpose. This, too, may possibly, in the near 
future, give way to the still more brilliant electric arc 


light. But the introduction of mineral oil, in conjunction 
with the adaptation of photography to lantern pictures, 
have been the main factors in giving the instrument its 
present popularity. 

The first lantern burning mineral oil, and called the 
Sciopticon, came to us from America. It was constructed 
on scientific principles, and was far in advance of anything 
of the kind before produced. It possessed good lenses 
and a powerful lamp, the two broad wicks of which were 
placed edgeways towards the condenser. The lamp was so 
closed in that it formed a combustion chamber, and burnt 
the oil under the best conditions. The lantern, however, 

" FIG. 3. 

had its faults. The front glass of the lamp was apt to 
break, and a dark vertical line was always seen upon the 
sheet a line which was in reality the image of the dark 
space between the two wicks. By adding a central wick, 
and by making certain alterations in the ventilation of the 
lamp chamber, Messrs. Newton conquered both these 
difficulties, and a far more perfect form of lantern has 


been the result. The same makers have, too, made the 
lamp distinct and separate from the lantern, so that, if 
required, it can readily be removed, and a lime-jet used 
in its stead. The form of lamp referred to is shown in 
fig. 3, both open for trimming and closed as in use, 
while a complete mineral oil lantern, of the kind 
now adopted by most makers, is seen at fig. 4. The 

FIG. 4. 

management of oil lanterns is so simple, really resolving 
itself into the necessity for keeping the burning wicks at 
a correct height, and putting the slides or pictures on the 
stage provided for them, that no more space need be 
devoted to this portion of my subject. 

The great advantage of using a pair of lanterns is that 
whilst a picture is being shown by one, another picture is 
being made ready in the other, and there is no pause or 
blank screen when the change is made. The so-called dis- 
solving views, which are produced by making this change 
slowly, made a great sensation when they were first intro- 


duced, perhaps because few knew exactly how they were 
managed. But they are now so common that many 
persons consider them rather tiresome than otherwise. 
Still, they give the operator a ready means of varying his 
work, if the dissolving apparatus be used with judgment. 
Thus most beautiful effects can be obtained in landscapes, 
more especially in seascapes, by using photographic 
cloud pictures, the gradual blending of one clouded sky 
into another giving fine aerial and very natural results. 
In one set of pictures which I prepared to demonstrate 
the beauties of cloudland, in connexion with a lecture on 

FIG. 5. 

ballooning, a sunrise picture was made to melt into a sun- 
set picture, and in due time this latter gave place to a 
moonlight effect. I am convinced that much can be done 
in this direction if time can be given to the preparation of 
the pictures. 


Originally for such effects two separate lanterns were 
used side by side, but now a biunial lantern, with one 
optical system above the other, is employed (see fig. 5). 
The modern arrangement is far more convenient for the 
operator, for the apparatus is compact and every adjustment 
is within easy reach of his hand. A lantern so constructed 
generally consists of a strong wooden body, lined with metal, 
with cells for the reception of the condensing lenses. 
Openings at the back shaped thus JL allow for the necessary 
to and fro motion of the lime jets and their trays. 
Between these openings, on the outside of the lantern 
body, is fixed the dissolving key or tap, connected by india- 
rubber tubes with the two jets (see fig. 6). In front of the 

FIG. 6. 

instrument are the stages for the reception of the slides, and 
the metal plates to which are affixed the telescopic tubes for 
holding the objective lenses. These plates are hinged, and 
their inclination upward or downward to make the two 
discs concentric on the sheet or screen is governed by 
milled headed screws. The objectives can by this means 
be made to slightly approach one another, while the con- 
densers remain fixed. It is obvious that it would be better 


if the condensing lens also moved with the objective so 
that the optical axis of one should agree with the 
other. This could easily be done by making the upper 
lantern move on a central pivot, and clamping it with a 
fixed screw ; but the more faulty and elaborate plan has 
been adopted by manufacturers, and will probably hold its 
own for a long time yet. 

It is certainly too much the fashion to adorn lanterns 
with a mass of heavy brass-work. Like any other adorn- 
ment, the brightly-lacquered brass looks well enough, but 
represents, to my thinking, a waste both of material and 
of workmanship, which adds greatly to the cost of an 
instrument, without adding one jot to its efficiency. In- 
deed, this brass-work is a positive disadvantage when a 
lantern has to be carried from place to place by a busy 
lecturer, and constitutes, not only an inconvenience, but a 
tax, in the shape of "excess luggage." This superfluous 
metal must, I suppose, be looked upon as a custom of the 
trade, which it is very difficult to break down. It is the 
same case with the microscope, the delicate brass-work of 
which often costs more than the lenses, expensive though 
the latter are. In each case the metal-work represents a 
convenience in operating the instrument, but much of it 
could be dispensed with, without in any way detracting 
from its performance. We may, I think, gain a lesson 
in the construction of an ideal lantern by examining 
a modern photographic camera for tourists' use, where the 
greatest rigidity is combined with extreme lightness, and 
metal is used but sparingly. Looking at such an 
instrument, we find that it must be extended for focus- 


sing purposes, and that its chief expanding part is made 
of folded leather (concertina bellows fashion). Now, why 
should not the same arrangement be adopted for the 
optical lantern ? We here require a similar extension of 
the front of the instrument, in order to suit the foci of 
the different lenses employed, and according to the dis- 
tance and size of the picture which we wish to project on 
the screen before us. Surely some arrangement of the 1 
kind could be adapted to the lantern. If such a change 
of construction were brought about, and with analogous 
alterations in other parts, the weight of a double or triple 
lantern would certainly be reduced to about one-third of 
of what it is at present. It may, perhaps, take some time 
for opticians to appreciate this view of the case, and there 
may be good trade reasons for not making a change of 
such a radical nature. I am not behind the scenes, and 
so cannot tell. It might certainly be urged with some 
truth that there is no need to be in a hurry to alter the 
present type of lantern, seeing that lightness of construc- 
tion may soon be brought about by the substitution of 
aluminium for brass. The production of the former 
metal is daily becoming cheaper, and as its weight, bulk 
for bulk, is about one-third that of brass, and as it is 
strong, not easily tarnished, and in other respects is suit- 
able for the purpose of lantern construction, we may look 
forward to its adoption in this service. 

Where a lantern is used for educational purposes it 
requires certain additions which are quite unnecessary in 
exhibition instruments. On the other hand, several 
ornamental adjuncts which are desirable in the latter 


form of lantern may be dispensed with in the instrument 
designed for the lecture or school room. Indeed, in an- 
other chapter I point out how a very simple arrangement 


of lamp and lenses can be made serviceable for educational 
work. One of the most important additions to an instru- 
ment used for teaching is what is known as the 
vertical attachment. The object of this arrangement 


is to show certain preparations and other objects which 
must be kept in a horizontal position during exhibition. 
" Horizontal Attachment " would, therefore, perhaps be a 
more sensible name for the apparatus the construction of 
which can be easily understood by reference to the annexed 
cut (fig. 7). The round opening in front, four inches in 
diameter, is the place where the apparatus fits on to the 
lantern, the lenses, &c., of the latter having been removed 
for its accommodation. So that the light from the lantern is 
received by the sloping mirror, and is reflected upwards 
through a condensing lens, which is placed horizontally. 
This lens forms a table or stage upon which different slides 
or preparations can be laid for exhibition. The image is 
formed by the lens above, and by the prism above that is 
redirected and cast upon the sheet or screen. It is obvious 
that some loss of light must result from filtering the rays 
through so many media, but this cannot be helped. In 
the chapter dealing with experiments possible with the 
lantern the use of this vertical attachment will be further 
alluded to, when its value will be better appreciated. 

Double lanterns to burn oil are usually placed side by 
side, but fig. 8 shows a convenient form of lantern which 
has been recently introduced, and which is so constructed 
that one lantern can be detached from its fellow. Thus, 
when the lime-light is used they are adjusted one above 
the other, and when the oil lamp is employed they are 
placed side by side. Mr. Tyler has still more simplified 
the matter by inventing a biunial lantern which burns 
oil, although the position of the two lamps is one above the 
other. This he achieves by the use of a bent chimney, 



which proceeds from the lower lantern and carries away 
the hot air, so that it cannot influence the lamp above. 


FIG. 8. 

In the triple lantern (fig. 9) we have three optical 
systems, and of course three lime-lights. This is the 
exhibition instrument par excellence , and is commonly 
used by those exhibitors who may be described rather as 
entertainers than lecturers. . The third lantern is in reality 
not often used. It is kept in reserve for producing occa- 
sional effects while the other two lanterns are at work. 

In some respects the optical lantern resembles the king of 
musical instruments, for the effects which can be produced 
by it are dependent upon and limited by the number of its 
parts. If an organ has but one row of keys, the instrument 
can do little beyond furnishing an accompaniment. With 



two rows its capabilities are much increased, for the organist 
can use them alternately in contrast with one another, or 
can combine them. With three claviers, his powers are 
once more amplified, and he can introduce those changes 
of musical colour for which our language provides no 
descriptive word. So it is with the lantern. If it have 

FIG. 9. 

but one optical system the operator can only use it as a 
means of showing simple pictures or diagrams. If it have 
two systems he can produce the popular dissolving views ; 
and if it be provided with a third set of lenses, he can 
mingle with the views shown those " effects," as they are 
called, which are so welcome to an audience of young 
folk, and very often to children of a larger growth. 



jHE three great essentials of a good optical lantern 
are the light, the condenser, and the objective, the 
two latter forming the optical system of the instru- 
ment. Theoretically, the light to give the best results should 
be a mere point of radiance, but unfortunately this is 
at present almost unattainable. I say almost, because I 
believe it to be quite within the bounds of possibility to con- 
struct an electric arc light which shall fulfil all the conditions 
as to steadiness, uniformity of action, and maintenance of 
a fixed position, which are required in lantern work. Such 
a light has not yet been found, but when electricity 
becomes more general as a source of illumination in our 
cities and towns, as it .surely will, an arc light or 
regulator of the required description will, I feel confident, 
soon be forthcoming. The invention of such a con- 
trivance, when the means of obtaining the requisite 
current to feed it is so limited, would at present have the 
disadvantage of coming before its time. The electric 
arc light has been used more than once experimentally 
in the lantern, with the most promising results. 



The best source of illumination for the lantern 
is, when we exclude electricity for the reasons just 
indicated, the lime-light. It has the good qualities 
of intense whiteness, steadiness, ease of management, 
portability, and although not a point, its area of radiance 
is not much greater than the space covered by a pea. I 
shall describe in detail the method of its production and 
management later on. 

Having then a convenient form of intense light, we have 
next to consider the means of using it to the best ad- 
vantage. We must start with the acknowledgment that 
in enlarging the image of a picture we must sacrifice a 
large amount of light. But by using properly-constructed 
lenses, we can make this loss as little as possible. As 
already pointed out, the optical system of a lantern 
consists of two distinct parts, the condenser and the 
objective lenses. 

As many of my readers may be quite unacquainted with 

FIG. 10. 

the matter under consideration, I will point out why this 
double system is necessary, and describe the work per- 
formed by each set of lenses. In the annexed diagram, 
fig. 10, L represents the lime cylinder, with rays of light 
emanating from it and illuminating the picture P, which 




we require to show in an enlarged form. is the objective 
lens by which this enlargement is to be brought about ; 
the sheet or screen upon which the picture is projected 
being supposed to be far away to the right. With such an 
arrangement of parts what should we see on that screen ? 
In the first place we should have but a very feeble light, 
for as will be seen by reference to the diagram, most of 
the luminous rays are wasted altogether, only the cen- 
tral ones proceeding through the lens 0. It will be 
seen also that these rays go through the central portion 
of the picture only, and that therefore only this part 
can be projected on to the distant screen. So that as a 
result of our first efforts at lantern projection, we get an 
indistinct and badly-lighted portion of a picture presented 
to us. How can we remedy this state of things ? Ob- 
viously, the thing to be done is to cause more of the rays 
from our light source to be utilised, and this can be brought 
about by placing between that light and the picture a lens 
which shall condense the light upon that picture, and which 
is therefore known as the condenser. 

In fig. 11 we see a repetition of the diagram, fig. 10, with 

FIG. 11. 

the addition of a condenser, shown in this case, for the 
sake of simplicity, as a single lens. Referring once more 


to this imaginary picture upon our screen, we now see that 
it is complete. It is no longer the central fragment of a 
design, but covers the sheet, and is equally illuminated. 
We can at once see the reason for this welcome change by 
looking once more at our revised diagram, fig. 11. The 
rays of light instead of being wasted in illuminating the 
inside of the lantern box, are refracted by the lens which 
we have introduced, and are bent towards the objective. 

In my diagrams, for the sake of simplicity, I have 
represented each lens as consisting of a single piece of 
glass of plano-convex form. Such lenses are found in toy 
lanterns of the cheapest kind, but are, as might be ex- 
pected, extremely faulty in performance. In the enlarged 
picture, they give, owing to their total want of correction, 
badly-defined margins, curved lines, and fringes of colour. 

Having now seen the purpose fulfilled by the condensing 
lens of the optical lantern, let us further consider its best 
form, and let me at once correct an error into which a 
purchaser is likely to fall. I have sometimes heard the 
possessor of a lantern speak somewhat boastingly of his 
instrument as one with 5, or perhaps 6 -inch condensers, 
the more ordinary size being 4 inches, and often only 
3 1 inches. For lantern projection, any size over 4 inches 
is a positive disadvantage, and instead of representing a 
gain, means really a great loss of light. The reason for 
this is readily seen. What may be called the standard size 
for a lantern picture is 3 inches in diameter (the entire 
slide with its margin measuring 3J inches). If the picture 
be framed in a circular 3-inch mount, a 3J-inch condenser 
will amply illuminate it. If, however, the orifice of the 



mount be square or cushion-shaped, such a small condenser 
would infallibly cut off the corners of the projected image, 
and for such pictures, therefore, a 4-inch condenser is 
necessary. But the smaller condenser transmits more 
light, for the reason that being of shorter focus, the lime 
cylinder is brought nearer to it. Some well-known 
exhibitors, seeing the great importance of getting all the 
light upon the screen that they possibly can, use nothing 
but 3J-inch condensers, but this obliges them to confine 
themselves to round pictures. On the whole, I prefer 
myself the 4-inch condenser, for although I lose some 
light, I can make use of any shaped pictures or diagrams 
which may be required. (If the lantern be used for 
photographic enlarging purposes, then a large-sized con- 
denser is the great thing needful, at least, we must have 
one of a size large enough to cover the negative which 
has to be enlarged ; a quarter-plate size necessitating a v 
5 -inch condenser and so on. But in that case brilliancy 
of image is quite a secondary matter, and is compensated 
for by extension of time occupied in the operation.) It 
must also be borne in mind that, quite apart from the 
question of focal length of the condensing lens, there is a 
limit to the near approach of the incandescent lime 
cylinder towards it, for the intense light is naturally ac- 
companied by a fervent heat, which will surely crack 
a lens if it be too near to ifc. In the chapter on the 
working of the lime-light, precautions against this accident 
are fully dealt with. 

There are two forms of condensers, either of which 
may be commonly found in commercial lanterns. One 



consists of a pair of plano-convex glasses mounted in one 
cell, with their curved surfaces all but touching one another. 
This form was, I believe, first introduced with the 
American sciopticon. It is shown at fig. 12. The other 
form of condenser is that devised (but not for lantern use) 
by Sir John Herschell, and which consists of a double 

FIG. 12. 

FIG. 13. 

convex lens, associated with a meniscus, the concave side 
of the latter being next the radiant point, as shown in 
fig. 13. In a good condenser we want not only quantity 
of light, but also good quality, and these properties can 
only be secured by careful attention to certain points of 
construction. Quantity of light is governed by size and 
focal length, as already pointed out, and it may be as well 
to indicate here the manner in which lanterns furnished 
with condensers of larger size than I have recommended 
may be made to transmit a greater amount of light by the 
interposition of another lens. There were at the old Poly- 
technic Institution some antique lanterns with 10-in. con- 
densers, this large size being necessary to cover the 8 -in. 
hand-painted transparencies which were in use before 
photography worked a revolution in such things. Such a 
large condenser, of course, meant a great loss of light, as 



already pointed out. So the suggestion was made that a 
small lens should be interposed between the light and the 
condenser. This was done with a wonderful gain in the 
performance of the old lanterns. Fig. 14 will show how 

FIG. 14. 

the additional lens brought this improvement about. Many 
other forms of condensing lenses have from time to time 
been suggested and experimented with, some of these em- 
ploying three or more combinations. But these various 
patterns, although one or two of them seem very promising 
in form, have not been taken in hand by makers generally, 
possibly on the score of expense, and probably owing as 
much to that hesitation and laziness common to human 
nature, which keeps us all to a well-beaten track. 

But a few years ago the question of lantern lenses was 
revived by a paper read by the late Mr. J. H. Dallmeyer 
before the Photographic Society of Great Britain. The 
reader of this excellent contribution to the subject, explained 
in the first instance that a well-known worker with the 
lantern h^cl called his attention to the great want of more 


perfect lenses for use with the instrument. Mr. Dallmeyer 
thereupon determined to tackle the subject, and produced 
new forms of condensers and objectives, a description of 
which he placed before the Photographic Society. I can- 
not do better than quote the description of the new eon- 
denser from this paper, and at the same time reproduce 
one of the drawings shown in illustration of the remarks 
made (see fig. 15) : 

FIG. 15. 

" The condenser is of 4-in. effective diameter, and 2J- 
in. equivalent focal length. Assuming the light to be at 
a safe distance of 2| in. from the flat surface of the first 
lens, this condenser collects an angular pencil of about 
66, i.e., about 20 per cent, more light than the shortest 
focus symmetrical. It consists of two unsymmetrical 
lenses, A and B. A is a plano-convex of flint 3|-in. 
diameter, and B is a double convex of crown glass of 4-in. 
diameter. The lenses are mounted at a certain distance 
apart, with their deep sides facing each other. Approxi- 
mate correction of chromatic aberration for centrical pencils 
is obtained by a proper apportioning of their focal lengths, 
and the distance at which they are placed. Thus : ray 


L R, after refraction by lens A, diverges into a prismatic 
beam; this falls upon different parts of lens B, which, 
while acting upon the two extremes, the red and the 
violet, in contrary directions to A, causes them to emerge 
parallel, the condition of achromatism, when they converge 
to the conjugate focus f, about 9 in. removed from B. The 
spherical aberration is reduced to a minimum by the forms 
of the lenses employed, i.e., ray Lr, refracted by the central 
portions of the lenses, meets the axis at the same point f, 
as the marginal rays, or nearly so. I have decided upon a 
4-in. (effective) diameter condenser, since it fully illumi- 
nates the corners of a 2|-in. square slide. Of course, a 
circular slide of 3 in. only requires a 3J-in. diameter con- 
denser, of proportionately shorter focal length. I need 
hardly say that the glass composing this condenser has 
been selected with especial care. It is perfectly limpid, or 
colourless, and will remain so ; it is free from stricB and air 
bubbles, and has a perfect polish. In fact, it is Chance's 
best glass ; the only drawback being its cost." 

Mr. Dallmeyer goes on to remark that the defects in the 
glass of a lantern condenser, are of far more importance than 
similar defects in the objective, so far as purity and quality 
of the illuminated disc are concerned. He refers to such 
defects as scratches, air-bubbles, and the like. In the case 
of an air-bubble in the objective lens, it is really of no 
moment whatever. I have known of a photographic lens, 
otherwise of splendid quality, being rejected because of 
a tiny air-bubble near its margin, the purchaser being quite 
content to exchange it for a far inferior lens without such 
an insignificant blemish. Such a bubble would have no 


effect whatever upon the performance of the lens, whether 
used with a camera, or as a lantern objective, supposing it 
to be suitable to lantern work in other respects. But 
transfer the bubble from the objective to the condenser, and 
it at once constitutes a real eyesore, which will be terribly 
magnified on the screen. For this reason lantern owners 
should take the greatest care to prevent their condensers 
becoming scratched, for a mark hardly visible on the glass 
will become fatally apparent on the screen. 

It will be seen, from what has gone before, that the duty 
of the condensing lens is to take up and utilise as large a 
bundle of light rays as is practicable, and with those rays to 
brightly illuminate the whole of the picture or slide placed 
against it. The other part of the optical system of the 
lantern is the objective lens, which is destined to 
form a magnified image of that picture or slide. To this 
important part of the apparatus I must now turn the 
reader's attention. 

As the duty of the condenser is to give the greatest 
amount of illumination to the lantern picture or slide, so 
the province of the objective lens is to form as perfect as 
possible a magnified image of that picture upon the screen 
or sheet placed for its reception. Toy lanterns are fre- 
quently fitted with a double convex, the worst form of all, 
or with a plain convex lens, which is little better. With 
regard to lanterns of more pretension, we find that different 
makers adopt different forms and combinations for their 
objectives. Some use a couple of plano-convex achromatic 
lenses, in conjunction with a stop or diaphragm, the flat 
sides of the lenses being next the light ; a very 


good form indeed, provided that the lenses are of sufficient 
diameter to take in the entire cone of rays from the con- 
denser. This has always been a stumbling-block in 
adjusting lenses of short focus to the lantern, for it stands 
to reason that the shorter the focus the nearer must the 
lens be to the condenser, and if the diameter of the 
lens be small a large proportion of the rays will not get 
through at all. 

And this question of focus of the objective is one that 
must be carefully considered by all who use a lantern. 
Many are of the opinion that the focal length of the objec- 
tive used should be so short that the distance of the 
lantern from the screen should be about the same as the 
diameter of that screen. In private rooms of small size 
this may be necessary, if not advantageous, but in larger 
rooms or lecture-halls a lens which will triple or quadruple 
that distance is desirable. Much experience of lecture- 
hall work has led me to the conclusion that a lens of 8-inch 
focus is more useful as a lantern objective than any other, 
and it is as well to have one of 10 inches in reserve in 
case the length of the hall should require it. Let me give 
my reasons for this choice. I find that the size of sheet 
most commonly required, in rooms used for lecture pur- 
poses is 15 feet. Some rooms will take an 18-foot sheet, and 
very few take a larger one than that. But the 1 5 -foot screen 
is the one most in request. Now let us suppose the operator 
has fitted to his lantern an objective of say 4|-inch focus. 
To cover his 15 -foot screen he must plant his lantern less 
than 20 feet from it, a distance which will land him in 
the middle of the front seats. His apparatus will 


in sack a case terribly impede the view of all those 
behind the lantern, besides causing much disarrange- 
ment of chairs. But let him use an 8-inch objective, 
and his lantern can he carried to a distance of 
35 feet from the screen. This will probably place the 
lantern quite at the back of the hall. Another point in 
favour of the latter position is, that if his two lenses are of 
the same diameter, as most probably they will be, the long, 
focus lens will admit more light, as already explained ; 
while it will certainly give better definition and less dis- 
tortion jbhan the shorter focus lens. One more circum- 
stance in favour of the longer focus lens is, that the lantern 
is kept more horizontal. When the instrument is close to 
the screen, unless the floor of the auditorium be inclined, 
as in a proper lecture-theatre, the lantern must be very 
much tipped up at its fore-end, so that the disc on the sheet 
shall be high enough. This raising of the. lantern, of 
course, leads to distortion, unless the screen be inclined 
towards the lens so as to compromise the matter. With a 
long-focus lens the distortion from this cause is greatly 
reduced, and very often it is so slight that there is no need 
to incline the sheet. I hold the opinion that a good single 
achromatic lens of long focus is by no means to be despised 
for lantern work, although a half-plate lens of the portrait 
type is to be preferred. Such a lens can only be used for 
the long-distance work. If it is absolutely necessary that 
the lantern be as near the sheet as possible, then it is com- 
monly the fashion to use a French quarter-plate photographic 
lens, I presume on account of its cheapness. For it is 
most difficult to select a lens of this description which will 


give a flat field, and the ordinary diameter of the back lens 
of such a combination will not admit the whole of the 
rays from the condenser : hence we are robbed of light, 
and very often of the corners of square pictures into the 

Of late years makers have seen these disadvantages, and 
have produced lantern objectives which, while they are 
similar in construction to portrait objectives, are made with 
much larger apertures at the back. Taking Mr. Dallmeyer's 
lantern objective as the prototype of these, we find that it 
consists, like the portrait lens, of two combinations. The 
back one, next the light, is a convexo-concave of flint, and 
another of crown glass, separated by a short interval, the 
two glasses being dissimilar in their curvature. The 
external form of this combination is a meniscus, its convex 
surface being next the condenser. The front combination, 
of smaller diameter, also has the external meniscus form, 
but consists, like its fellow, of two glasses. 

It must be noted that objectives made for lantern work 
are not suitable for photography, for the visual and chemical 
rays are not coincident. I mention this for the sake of 
those who wish to use the lantern as an aid to their photo- 
graphic pursuits, in enlarging and so on. It may^theref ore, 
be in some cases desirable for the purchaser to obtain a 
half -plate portrait lens for his lantern. It will do excellent 
work, with the limitation already referred to, while at the 
same time it can be used either for portraiture or for 
enlarging. For both these uses it is well adapted. 

The rule for calculating the distance of the lantern from 
the screen in order to obtain an image of a given size will 


be found on page 95, bat in practice I find it a convenient 
thing to use a tape measure. Upon the circular case of 
this measure I have certain figures to the effect that such 
and such a lens requires a distance of so many feet to give 
a 15 or 18 foot disc. The place of the sheet having been 
decided upon, it is then easy enough to pay out the 
required amount of tape, and to fix the position of the 



[HE first requisite for the lime-light is an adequate 
quantity of oxygen gas, and this chapter will, 
therefore, be devoted to the details of its manu- 
facture, or rather its separation from those substances with 
which, in nature, it is associated. For, although the most 
abundant of all the elements, oxygen does not occur in 
the uncombined state, and, therefore, the chemist has to 
be at the pains of separating it from its various yoke- 
fellows. There are several methods of obtaining this gas ; 
the greater number of which, being only of experimental 
interest, may be passed over. 

The gas was originally discovered by Priestley in 1774, 
and at about the same time, independently, by the Swedish 
chemist, Scheele. Priestley obtained it by heating mer- 
curic oxide in a flask, which substance, under such treat- 
ment, breaks up into mercury vapour and oxygen gas. 
Such a method is clearly out of the question, when several 
feet of gas are required for the lime-light. 

Another method, which is applicable when large quan- 
tities of oxygen are wanted, and which has long been 


adopted on a commercial scale, depends upon the action of 
cobalt on bleaching powder (Calcic hypochlorite). The 
lime must be in the form of a concentrated solution, and 
this is best brought about by mixing, say, one pound of 
bleaching powder, which is commonly called chloride of 
lime, with a quart of water. Stir this mixture and allow 
it to remain for an hour. Now decant the clear liquid, 
and pour it upon a fresh pound of lime stir as before, 
and strain the product through a calico or flannel bag. 
Place the liquid in a large bottle, to the cork of which 
a tube is fitted. Now drop into the liquid, taking the 
cork out for the time being, a small quantity (say 2 ounces) 
of a strong solution of cobaltic peroxide, when oxygen gas 
will be quickly evolved, and will come off through the 
replaced tube. The evolution of gas is increased by 
warmth. The same cobalt can be used again and again, as 
it does not undergo any permanent change. It seems to 
act merely as a conveyer of oxygen, taking it from the 
lime, passing it to a higher state of oxidation, and then 
giving it up again ; any solution of cobalt will answer the 
purpose. When the gas ceases to come, the residue in the 
bottle should be diluted with water, and, after having been 
allowed to rest for some time, the cobalt will settle at the 
bottom of the vessel. This can then be washed, kept in a 
moist state, and used over again as often as required. 

But the more general method of preparing the gas is by 
means of the decomposition of potassic chlorate, and 
that method I shall now, therefore, describe in detail. 

The lime-light has, in certain quarters, earned the cha- 
racter of being dangerous, not so much from accidents 



which have occurred during its use, but more from certain 
catastrophes which have taken place during the preli- 
minary operation of making oxygen gas. There should be 
no danger whatever about this operation if only ordinary 
precautions are taken. But some people seem to be unable 
to do things except in a haphazard manner, and they 
sooner or later pay the penalty for their carelessness. 

The most important point to begin with is to have 
proper apparatus ; and by this I do not mean the most ex- 
pensive, for this is just as often as not faulty in point of 

FIG. 16. 

construction. The articles required are : A retort in 
which to generate the gas; a stove for heating that retort 
(preferably a gas ring-burner) ; a wash bottle, or purifier ; 


several feet of good rubber tubing ; and a bag to hold the 
gas when made. The retort which I prefer is Oakley's 
pattern, and is made of wrought iron, brazed and rivetted 
together, and of the form shown in the accompanying 
sketch, fig. 16. It will be noticed that it is of conical form, 
and that its lower part, where it rests on the stove, is con- 
vex in shape. It terminates at the mouth with a brass 
screw, and in this screw fits a branch, or pipe, which con- 
veys the gas away as fast as it is generated. An important 
point in this branch is the arched bend, immediately over 
the retort, which obviates undue friction, and also prevents 
any solid particles given off from the retort clogging or 
stopping up the tube. With that provision one element 
of danger is avoided. Another point of importance is the 
little upright tube, or nozzle, immediately above that same 
bend. This is merely a short piece of tubing fixed on to 
the branch, and in which a cork can be fitted. This acts 
as a simple safety-valve. Should the pressure of gas 
become too great, the cork will fly out and no damage can 
possibly occur, except the loss of a very small quantity 
of gas. 

There are various other forms of retort which are used 
and recommended by different operators. A cast-iron one 
is, of course, more lasting ; but in case of accidental explo- 
sion, its particles would be as deadly as those of a bomb- 
shell. But such an explosion should never occur, if 
ordinary care be taken. With some persons, familiarity 
with the most dangerous agents so rapidly breeds con- 
tempt, that they get careless in a very short time. We 
may suppose that this happened in the case of an optician, 


who some years ago was killed by such an explosion of an 
oxygen retort. 

Many old-fashioned operators use an iron mercury 
bottle as a retort, and this, I believe, was the invariable 
custom when oxygen was procured from manganese per- 
oxide alone. The heat required was so great that a thick 
and lasting receptacle was necessary. But now-a-days, 
when chlorate is used so universally, the gas comes off at a 
much-reduced temperature, and a thin retort will last, with 
care, for about fifty charges. My lantern assistant prefers 
to use a kitchen digester, which he has had fitted with 
a pipe and safety cap, and which he regards as a triumph 
of art, which will not only last his own life-time, but will 
be handed down to his descendants as an heir-loom. One 
more word on the subject of retorts. Do not buy a copper 
one ; it is very expensive, and quickly wears out, and has 
no advantages whatever. In case a retort should be 
wanted in a hurry, and cannot be obtained, a common 
cast-iron kettle is a capital substitute for one. Put the 
chlorate mixture in the kettle, and fasten on the lid with 
a luting of white lead or clay ; cut a piece of firewood 
to the correct size, to fit tightly between the lid and 
the inside of the handle of the kettle, so that no pressure 
will force it open. Use the spout as a delivery tube of the 

The retort is charged with a mixture of chlorate of potash 
and oxide of manganese, and the most usual proportions 
are four parts by weight of the potash to one part of the 

This is the mixture as given in the various chemical text- 


books ; but, as a matter of fact, the exact proportion is not 
of very great consequence. Indeed, it would seem that if 
the crystals of potash have mixed with them just sufficient 
of the black manganese to dirty them well, the mixture 
will be effective. 

Oxygen gas can be generated from the chlorate alone, 
but the action is so uncertain that the salt is always mixed 
with manganese, oxide of iron, or sand. What action the 
manganese has upon the mixture is not known, for it is 
a curious fact that, after the operation is over, it remains 
unchanged, so that it is possible, if one cared to take the 
trouble, to preserve it and use it over and over again. 
Where manganese is difficult to obtain, this method may 
be adopted, but in most towns it can be procured at such 
a cheap rate that such a course would simply represent a 
waste of time and trouble. 

The greatest care should be exercised in procuring both 
components of the oxygen mixture in an unadulterated 
state. The ordinary commercial chlorate is quite good 
enough for the purpose, and although it has the disadvan- 
tage of being contaminated with a certain amount of free 
chlorine which is given off in gas-making, it would be 
a useless expense to employ the pure salt, as used for 
medicinal purposes. Moreover, the chlorine can be got rid 
of, as we shall presently see, by simple means. But in 
most samples of commercial chlorate there are to be found 
certain foreign bodies, such as bits of straw, bits of wood 
(from the casks in which the chlorate is originally sold), 
and other specimens of matter in the wrong place, which 
would be prejudicial to the operation of gas-making, and, 



indeed, dangerous ; for carbonaceous material, when mixed 
with, the chlorate, constitutes a very powerful explosive. 
(As an instance of this, I may mention that in the greatest 
explosion of modern times, when thousands of tons of 
explosive material were fired for the purpose of destroying 
the "Hell-Gate Bock" at the entrance of New York 
Harbour, a large proportion of the chemicals employed 
consisted of chlorate of potash combined with coal-dust.) 
Before mixing the ingredients together, therefore, the 
crystals of potash should be carefully picked over by hand, 
and any unconsidered trifles which have no business to be 
present should be carefully extracted from it. A little care 
is also necessary with regard to the manganese. Accidents 
have happened from lampblack, bone-dust, and other similar 
compounds, having been substituted (let us hope by acci- 
dent) for the manganese that was intended to be used. In 
buying fresh samples, therefore, of manganese, it should 
be carefully tested, and the best way of doing this is to mix 
up a small quantity of the potash and the manganese in 
the proportions above given, and to put them in a test 
tube, which should be held over the flame of a spirit lamp. 
If the mixture simply sparkles while oxygen gas is given 
off at the mouth of the tu-be (as may be tested by the spark 
on a blown-out match), the mixture is safe ; but if any- 
thing in the least resembling an explosion should take place, 
the manganese is wrong, and must be rejected. But the 
operator is not liable to fall into the error of mistaking 
lampblack or bone-dust for manganese, because they are, 
bulk for bulk, so very much lighter than that heavy 



The mixture having been made, enough of it must be 
placed in the retort to give the amount of gas which we 
require. It will be found that if we allow one pound of 
chlorate to every 4 feet of gas, it will be about right. 
Roughly speaking, a bag of 8 feet capacity, a very useful 
size, will take 2J Ib. of the mixture, and it is better to 
waste a little chlorate than to have a bag which is not 
quite full. Having charged the retort with the mixture, 
we can screw on the delivery branch, taking care to insert 
a washer of leather or asbestos cloth, to prevent any escape 
of gas between branch and retort. 

In using a new retort, it is always well to blow 
into it while the branch is fixed in position, so as to be 
quite sure that there is no leak in the joints which has 
escaped the maker's attention. Should a 
leak be discovered, a little white lead will 
remedy it for the time being. The retort 
may now be placed on the gas-stove, while 
its branch rests upon a chair or other 
support. A tube at least 4 feet long, and 
of a diameter agreeing with that of the 
branch of the retort, should be drawn 
over that branch for about 2 inches. The 
other end of this tube is to be connected 
with the wash-bottle. 

The kind of wash bottle which I 
use, and which I can recommend very 
highly, is also made by Oakley & Co. Fl . 17. 

of Bermondsey (fig. 17). It is of half a gallon 
capacity, and is in reality a glass "Winchester quart" 



bottle with a wide neck, such as can be obtained anywhere. 
Upon this neck fits a disc of lead, perforated with two holes, 
in which are soldered as fixtures two pewter tubes which 
bend away from one another at their tops. 

One tube, A, reaches nearly to the bottom of the bottle, 
and it will be seen that for several inches along its lower 
part it is perforated with holes. It is this tube which is 
connected by a rubber pipe to the retort. The dotted 
line shows the height to which the bottle must be filled 
with water. The short tube, B, is the delivery tube of 
the bottle, and is connected with the gas bag. As a gas- 
tight connexion between the pewter disc and the bottle, 

FIG. 18. 

there is a thick rubber collar, which is tied on the bottle 
by means of a piece of strong twine. The larger sectional 
diagram of the bottle neck (see fig. 18) will assist the 
reader in noting the arrangements described. In order to 
prevent any chance of water being thrown up into the gas 
bag, it is as well to place the bag on a table. Let us sup- 


pose that this has been done, and that everything is ready 
for making the gas. 

The stove should be lighted and turned down almost to 
its lowest point, for it is as well to begin with a small 
amount of heat, although I believe that it is the practice 
of some workers to begin with a full heat, and to turn the 
supply down when gas commences to come off. The tube 
is joined to the retort and to the wash bottle ; but the 
tube joined to the delivery end of the bottle is for the 
present left free at its other end. After an interval of 
about five or six minutes, the water in the wash bottle 
should show by its bubbling that the gas is being generated, 
but those bubbles are not as yet pure gas, but are partly 
air which has been contained in the retort, and which is 
expanded and driven out by the heat. We must wait 
some time longer, until these bubbles are given off 
with regularity, before attempting to fasten the open 
tube to the gas bag ; and before doing so it is as well 
to apply the test of the blown-out match to the free end of 
the rubber tube. If the spark on the match bursts into 
flame directly it is applied to the tube, we may be sure that 
gas is coming off in earnest, and we can by a dexterous 
movement fasten the tube on the tap of the gas bag, at the 
same time turning on that tap. 

Everything should now go on with regularity and with- 
out attention, until the bag is nearly half full. During 
this time it may be noticed that the tube leading from the 
retort will emit a kind of bubbling noise. This is due to 
water lodging there which comes from the crystals of 
potash in the retort. By simply lifting this tube up, and 


by giving it a gentle pinch for half a second the sudden 
ontrush of gas into the wash bottle will drive off any water 
that has settled there. When the bag is half full there is 
gene^a-Py a lull in the operation, and no bubbles are seen 
he water in the wash bottle ; and this opportunity 
may ^ssnoaken for turning on a little more gas, but not 
much more, for presently the oxygen will run off with 
redoubled vehemence, and if too much flame is applied to 
the retort the pressure may become too great for the con- 
nexions, or the cork of the safety valve may fly out. By 
governing the amount of gas supplied to the stove, the 
emission of oxygen can be very carefully regulated. (This 
regulation becomes still easier if a certain amount of 
common salt be added to the gas mixture in the retort. 
This should be done just before the retort is charged. The 
proportions are as follows : 

Chlorate of potash ... ... ... 8 parts 

Manganese ... ... ... ... 2 

Common salt ... .., ... ... 1J 

all by weight. When common salt is thus added to the 
gas mixture, the chlorate should be powdered.) 

When the gas bag is full: and " as tight as a drum," the 
various parts of the apparatus used in making the gas 
must be disconnected, and here some caution is necessary. 
The first thing to do is to pull the tube from the gas bag 
and turn off the tap at the same instant. Next remove 
the tube from the retort, and last of all turn off the gas 
supply from the stove. Why I say that caution is necessary 
here, is, because if the gas is turned off before the retort is 


disconnected from the wash bottle, the water in the latter 
may rush back into the retort and cause a small steam 

This has certainly never happened to me ; but I b^ve 
heard of cases where such a thing has occu: 1 

although it would probably be unattended by any id 1 1 tous 
results, it might lead to a great deal of mess and 

The retort may be left, until it has become nearly cold, 
or at any rate until it is cool enough to be handled. The 
branch pipe should then be unscrewed, and the retort at 
once washed out with water warm water by preference. 
This should be thoroughly done, and many changes of water 
should be used, until the last wash water comes away per- 
fectly clean. If the retort is left with the residue of the gas 
mixture in it, the metal inside is very quickly corroded, and 
the vessel does not last half so long as it does if it be at 
once carefully washed. The branch and the india-rubber 
connecting tubes should be washed out also. 

I have mentioned that* the commercial chlorate of potash 
is contaminated with a certain amount of free chlorine. This 
soon renders itself evident if the operator places his nose 
near the delivery tube from the wash bottle when the gas 
is coming off; for chlorine gas has a suffocating odour. 
This is not the only disadvantage which it has in gas 
making for lantern purposes, for it so acts upon the india- 
rubber bag and the attached brass work that it quickly 
leads to deterioration. By placing in the wash bottle 
water something which will seize hold of this chlorine and 
detain it, we shall avoid this last difficulty, and the 


best substance for the purpose is caustic soda, or 
potash, Failing this, common washing soda will answer 
nearly as well. Caustic soda is rather an awkward thing 
to travel about with, for it is of a most corrosive nature ; 
but it should be used in preference to anything else, when 
gas is made at home. Fragments of disused lime cylinders 
will also answer well. 

To show that the chlorine is actually taken up by the 
bag and its belongings, I may mention that if the experi- 
ment be tried it will be found that the gas when first made, 
although highly charged with chlorine and inducing 
coughing and other unpleasant sensations if inhaled, may, 
after having been left in the bag for an hour or two, be 
breathed without any ill effect. 

Mr. Fleuss, whose diving and life-saving apparatus de- 
pends in a great measure upon a supply of compressed 
oxygen gas, called my attention to the above fact, and told 
me that he had used gas for breathing purposes which had 
been freed of its chlorine by remaining in the gas bag for 
some hours as I have just explained. 

I may mention that the residue left in the retort and 
which I have recommended, should be washed out without 
delay, consists of chloride of potash, and the manganese ; 
the latter quite unaltered. It may be useful to point out 
that the difference between the chlorate and the chloride is 
easily seen by examining the crystals of each under a 
microscope. If a little chlorate mingled with water is 
placed on a slip of glass, and allowed to evaporate, the 
crystals will have a rhombic form (see A, fig. 19). But if, on 
the other hand, a solution of chloride of potash be examined 



in the same manner, they will be found to be square in out- 
line, as in B. Should it be desired to use the manganese 
over again, it must be freed from the chloride by repeated 

FIG. 19. 

changes of water. It will thus be dissolved out, while the 
manganese remains behind in the form of black mud. 
This latter must be dried before being again employed in 
the retort. 

The operation of oxygen gas making is now with many 
lanternists a thing of the past, for they prefer to buy it 
ready made. For many years this gas has been supplied, 
by one or two makers, compressed in iron or steel 
cylinders. But the price, eightpence per foot, was too 
high to induce consumers to relinquish the custom of 
making it themselves. Of recent months, however, the 
gas has been supplied at half that price, with the result that 
many prefer to buy it rather than make it themselves. 
The manufacture of oxygen gas therefore represents "A 
curious new industry," and under that title I described it a 


short time ago in an article in " Chambers's Journal." From 
that article I will now give the following extract : 

" Any manual of chemistry will inform us that oxygen 
is the most widely-diffused element in nature. It enters 
into the composition of air, of water ; it is found in nearly 
all earths and rocks; and forms more than one half of 
animal and plant life. In fact it is not too much to say 
that oxygen forms one-half of the globe and its belongings ; 
but of course it is combined with other elements. Chemists 
can tell us of a dozen different methods of isolating this 
gas ; but the one most usually adopted is to'subject a salt of 
potash (potassic chlorate), which is extremely rich in 
oxygen, to heat in a retort, when it quickly parts with that 
gas, which can be collected in a suitable containing vessel 
for use. To show the extent to which this salt is used for the 
production of oxygen, we may mention that we were lately 
informed by a London dealer that he sold yearly one 
hundred tons of potassic chlorate, and that he had reason to 
believe that it was nearly all used for the production of gas. 
This quantity of the salt would afford, roughly speaking, 
nine hundred thousand cubic feet of oxygen, and we must 
not forget that this is the amount dispensed through one 
dealer only. The natural question which arises as to what 
purposes this gas is applied, we shall deal with presently. 
We have preferred to show, first, that there is an enormous 
demand for oxygen, so that the importance of a new 
industry for producing it may be at once appreciated. 

" Oxygen forms one-fifth of the air which we breathe, the 
other four-fifths consisting of an inert gas called nitrogen. 
And it is important that we should remember that the 


mixture of these two gases is a strictly mechanical, not a 
chemical one. What we mean is this. If it were possible 
by any means to make visible and magnify the particles of 
air, we should be able to distinguish the atoms of oxygen 
and of nitrogen side by side, but in the proportion of one 
to four. It might be compared to a mixture of pepper and 
salt, which, although it looks gray to the unaided sight, 
would, under the microscope, show plainly the independent 
grains of both constitutents. (It is curious to note that a 
chemical mixture of the two gases, in which their atoms 
combine to form a new compound, produces that useful 
anaesthetic, nitrous oxide laughing gas.) It has long 
been the dream of chemists that oxygen might be produced 
direct from the atmosphere by separating its atoms from 
the atoms of nitrogen with which it is associated but not 
combined. Indeed, a plan by which this could be accom- 
plished has long been known, but it happens to be one of 
those numerous method which in theory are perfect, but 
which when reduced to practice are found to be encumbered 
by various difficulties. But as a new industry is founded 
upon the process referred to, and its success has been 
assured by a patient conquest of the numerous practical 
difficulties associated with it, we cannot do better than 
describe it. 

" It was long ago demonstrated by Boussingault that when 
the substance called baryta, otherwise the oxide of barium, 
was heated to a low redness, it would absorb oxygen from 
air submitted to it. He further showed that if this com- 
pound were then raised to a higher temperature, the 
oxygen thus absorbed would be given off once more, and the 


baryta would be restored to its former condition, ready 
for a repetition of the action. It would thus seem that 
there was at hand a process for obtaining from the atmo- 
sphere an endless supply of its essence, so to speak. But 
as we have before hinted, theory and practice are two 
different things. The process would not work on a com- 
mercial scale. All went well at first ; but for some reason 
or other, the baryta lost its power of recovery, and would 
not repeat its office of absorbing oxygen. 

" A few years ago, two of M. Boussingault's pupils, Messrs. 
A. and L. Brin, resolved to carry through a series of ex- 
periments to find out, if possible, why in this case, practice 
would not endorse theory. They soon found that the reason 
why the baryta lost its power of absorbing oxygen was due 
to certain molecular changes, which ceased to occur if 
the air supplied was absolutely free from impurities, and if 
the heat employed for reducing the baryta to its first 
condition were kept within certain limits. They further 
found that the necessary temperature might be much 
reduced if the material were heated in a partial vacuum. 
Another advantage was found in supplying the air under 
pressure, in which case the absorption of oxygen from 
it was much increased. These new conditions were speedily 
realised in apparatus which was erected in Paris, and which 
for three years yielded oxygen of the purest description 
without any renewal of the baryta with which the retorts 
were charged at the commencement of operations ; and this 
apparatus was exhibited at the Inventions Exhibition at 
South Kensington a few years ago. 

" The process having thus been shown to be workable, the 
inevitable Company was formed ; and oxygen can now be 



obtained in any quantity at a cheap rate by any one who 
requires it. Erin's Oxygen Company has established ex- 
tensive works at Westminster, where, by a system of 
retorts and air-pumps, the business of abstracting oxygen 
from the air is continuously carried on. The gas is carried 
to a holder, in which it is stored ; and is drawn from that 
holder and compressed in steel cylinders for the use of the 
Company's customers. These cylinders are so strong, that 
one having the capacity of little more than a cubic foot of 
gas will hold forty feet when that gas is compressed within it. 
These bottles, placed in wooden cases, are now sent over 
the kingdom by rail and carrier." 

The gas is of the utmost purity, and is largely used for 
charging water for drinking purposes, as a remedy for 
certain diseases. 

The following table gives the sizes of the cylinders 
supplied, together with their length and weight : 






Contents in 











6 Jib. 























Cub. contents. 




10 ft. 


10 in. 


20 in. 


39 Ib. 


Each cylinder is fitted with a tap to regulate the flow 
of gas, which tap has a nipple over which the rubber 
tubing can readily be drawn. The 
advantage of using a bottle instead of 
a bag in the one point of bulk is re- 
markable, as may be seen by the above 
table. Thus, six cubic feet, which will 
be sufficient for an hour and a half's 
entertainment, is contained in a re- 
ceptacle about the size of a champagne 
bottle, and which can be placed in 
the empty lantern-box during use. 
The amount of gas in a bottle can be 
readily ascertained by the use of a 
proper pressure gauge. In fig. 20 one 
of these cylinders is shown with the 
regulator and pressure gauge attached. 
The latter is of the form commonly 
used on steam engines, and is known 
as Bourdon's pressure gauge. It depends for its efficiency 
on the action of internal pressure upon a curved tube of 
oval section. The greater the pressure the straighter the 
tube becomes, and this movement is communicated by 
simple gearing to the index-finger. The following table 
will be found useful to those who employ compressed gas : 

Fig. 20. 
































1350- 9 






1200- 8 






1050- 7 




900- 6 




750- 5 




600- 4 








300- 2 




150- l 
















360- 8 



270- 6 











HEBE are three forms of jets for the lime-light, 
namely, the oxy calcium, the blow-through, or 
safety form, and the mixed jet. The simplest 
of all is the first named. 

The oxy calcium jet consists of a spirit-lamp, which is 
fed from a little reservoir at the back of the lantern. The 
spirit furnishes the necessary hydrogen, and through its 
flame a jet of oxygen is passed, and impinges upon a 
cylinder of lime placed just at the other side of the wick. 
This lamp will well illuminate a disc of about ten feet in 
diameter with a clear, white light. It has the advantage 
of simplicity, but presents one difficulty in the circum- 
stance that the lantern must be kept perfectly level. If it 
is inclined backwards, the spirit cannot flow to the point of 
combustion, and if it -is inclined forwards the fluid may 
flow too rapidly towards the wick. In some forms of 
oxycalcium lamp this is obviated by a special construction 
of the spirit cistern, which is furnished with an automatic 
valve for governing the supply of fluid to the wick. The 
wick will rapidly become charred if the stream of oxygen 



is allowed to impinge upon it; it should be so adjusted 
that the gas just escapes touching it while passing through 
its flame. This form of lamp is sometimes fitted with a 
wick of asbestos, which well resists the greatest heat that 
can be brought against it. The oxycalcium lamp is valu- 
able where no hydrogen gas can be obtained, and, while 
far more powerful than a mineral oil flame, can hardly be 
considered sufficiently powerful for use in a public lecture 
hall. It is used in many of the hospitals in conjunction 
with a simple form of lantern for throwing light upon 
patients during certain operations. 

Before I reached the mature age of 
twelve I had made oxygen gas by 
nearly every available method, and had 
used in this work sundry blacking 
bottles, ginger-beer bottles, gun-barrels, 
and gas-pipes, employing as gas-bags 
disagreeable bladders fresh from the 
butcher's. It is a wonder to me that 
I was never blown skywards, but 
blown-up in a figurative sense I often 
was. It is now my turn to assume the 
position of "stern parent," but in doing 
so I soften towards the juvenile ex- 
perimenter in memory of my own 
misdeeds. Perhaps a description of 
my first lime-light jet, made at 
the cost of a few pence, of two FlG - 21 - 

gasfitters' blowpipes, will answer the purpose better than 
anything else, of demonstrating the principle of the ordi- 



nary blow -through, or safety jet, which, on the whole, is 
the best form of burner for amateurs to adopt (see 

% 21). 

A isja piece of wood rounded off at one side of its upper 
end, as shown, so as to accommodate its form to the bent 
blow-pipe, which is marked 0, for this pipe is the conveyer 
of the oxygen. This is fixed in position by loops of wire, 
passing through holes in the wooden support. Upon 
the other side of this support is bound in like manner 
another blow-pipe, which has its fine nozzle cut off. This is 
marked H, for hydrogen, and is connected when in use 
by means of an india-rubber tube, to the house-gas supply. 
The upper points of these two pipes are so adjusted that 
the oxygen gas will blow through the flame from the H 
pipe, on to the lime cylinder L. A jet formed on this 
principle has the word " safety " linked to it, because the 
two gases are kept quite separate until they meet at the 
point of com bustion. Singly, they are innocent of harm ; 
but mixed, except under certain precautions, as we shall 
presently see, they form an explosive compound second 
only to gunpowder. 

To say that the arrangement thus described and illus- 
trated is anything but faulty in construction would be 
absurd, but I will say that there are many jets sold of 
far more pretension which give no better light, and cost 
as many florins as this one does pence. But as I have 
said, I have described it as a ready means of explaining the 
principle of the blow-through jet. I have tried many 
different patterns of jets, and have selected the one illus- 



trated at fig. 22 as being by far the most perfect of any of 
the blow-through type. 

FIG. 22. 

In selecting such a jet the buyer should be carefal to 
see that the orifice of the O pipe is sunk within that which 

FIG. 23. 

supplies the hydrogen, as shown at M. In many jets the 
two pipes are brought to the same level, but the form I 


illustrate gives a much better light, probably because the 
two gases are better mixed before reaching the lime. L is 
the pin upon which the bored lime cylinder rests, and it 
can be moved to or from the jet by means of the shifting 
screw S. K is a rod which extends outside the lantern, 
and which is for the purpose of turning the lime cylinder. 
The form shown is one commonly met with, and it consists 
of a rod connected with a bent spiral of wire. I have 
long ago discarded this arrangement, as it works by fitful 
starts, and jerks the lime round instead of moving it by 
degrees. The form of lime-turner attached to the jet 
shown at fig. 23 is the one to select. 

This form is known as the mixed jet, by which the most 
powerful form of lime-light is obtainable, but, as already 
pointed out, it is not so suitable as the one before described 
for amateur use. Both gases must be under the same 
pressure, therefore two bags for and H respectively 
must be employed, usually under the same pressure boards. 
The jet is safe enough in skilled hands, but is not so, 
unless care be taken with every detail. The two gases 
are led to the box or chamber W, where they mix, and 
impinge upon the lime through the single jet J. D repre- 
sents a recent improvement which I believe was first 
suggested by that very good authority on lantern matters, 
Mr. Lewis Wright ; it deals with the manner of turning 
the lime cylinder, so that it may not become pitted by the 
continued action of the jet upon one spot. The primitive 
plan was to open the lantern door at frequent intervals, 
and to give the hot lime a hasty touch with the finger. 
Next the lime pin was furnished with a screw which could be 


worked outside the lantern, so that it was turned and raised 
by the same action. But, strange to say, the screw was of 
so fine a pitch, as in fig. 22, that by one revolution the 
pitted part of the lime was once more brought under the 
influence of the jet. In Mr. Wright's arrangement, which 
I have long ago adopted, the screw is a spiral, which 
during one revolution raises the lime quite a quarter of an 
inch. This plan has still further been improved upon by 
the addition of a nicked wheel, which prevents the lime 
being turned by the operator more than is necessary for 
the time being. This addition is known as " Newton's 
Improved Check-action Lime-movement." The same firm 
of opticians have carried out a still further improve- 
ment devised by Mr. Andrew Pringle. This consists 
of what is called a " cut off," and is applicable only to 
the mixed gas jet. It gives the operator the means of 
setting his jet so that the gases are giving the best pos- 
sible light, and then by the turn of an extra tap cutting 
them off, with the exception of a small supply of the 
hydrogen which keeps burning. He can, therefore, adjust 
his lights beforehand, and feel confident that a turn of 
the tap will once more render them at their best at a 
moment's notice. 

There is certainly room for improvement in the manner 
in which lime jets generally are supported in the lantern. 
A metal tray, sliding in grooves, forms a base board, at the 
end of which is an upright rod of iron which, during use, 
projects at the back of the lantern. Upon this vertical 
rod the whole jet can be moved up or down, and can be 
clamped in position by means of a couple of screws, witli 



milled heads. The arrangement is by no means a good 
one, but it is one of those simple things which have been 
unheeded by the many, and manufacturers generally have 
adopted it without perhaps thinking how inconvenient it is 
in practice. In the first place, the jet is apt to slip either 
downwards bodily, or to one side or the other by a careless 
touch of the operator's hand. In either case, such a shift- 
ing of the light out of the optical axis causes the disc to be 
darkened until the jet be readjusted, which cannot be 
easily done without opening the door of the lantern and 
letting out a flood of light in the darkened room. There is, 
besides, much trouble in getting the jet central, which could 
easily be avoided by a more rational arrangement. Mr. 
Pumphrey, of Birmingham, has devised for the purpose a 
horizontal and vertical rack motion, very like the same 
movement which is attached to the mechanical stage 
of a microscope, but it is somewhat expensive, and 

FIG. 24. 

adds extra weight to the lantern. There is no doubt, 
at the same time, of its effectiveness and conveni- 


ence. A simpler plan is that recently introduced by Mr. 
Steward, and shown at fig. 24. In this case a tongue of 
metal is fixed to the supply pipes of the jet, and this 
tongue has a slot in its centre, which engages a vertical 
pin on the lantern tray. This pin is threaded so that a 
couple of discs can firmly clamp the metal tongue when 
the jet has been once centered. Once clamped in this 
way, the jet cannot be moved until it is released by 
unscrewing the discs. 

Another valuable improvement is represented by Wood's 
lime cylinder shield, which is shown, fitted to a jet, at 
fig. 25. It consists of a metal cylinder, rather larger than 

FIG. 25. 

the lime, in which the latter is free to turn. There 
is an opening in front, through which the incandescent 
lime can throw its light towards the condensing lens. 
In jets, generally, the lime is quite exposed, and unless it 
be gradually heated will often crack to pieces, by the 


unequal expansion which it undergoes. The shield pre- 
vents this by confining the heat within a narrow area 
around it, at the same time keeping the lantern itself com- 
paratively cool. Mr. Wood tells me that there is an 
undoubted gain of light from this conservation of heat in 
and around the lime cylinder. The shield, moreover, does 
much to obviate a by no means uncommon accident, 
namely, the fracture of the valuable condenser itself from 
a flame deflected towards it from a cracked or much-pitted 
lime cylinder. 

The most general method of storing the gases required 
for the lime -light is by means of bags, which should be of 
the best quality. It is necessary to caution the beginner 
on this point, for I have known cases where a perfectly 
new bag, fresh from the maker, has been found, on trial, 
to leak badly. I cannot say that such an unpleasant cir- 
cumstance has happened to myself, for I go to a maker 
upon whom I can rely. It may possibly have been the 
fault of the operator himself, who did not take the pre- 
caution to warm the bag before use. For these bags in 
winter time when of course they are most generally used 
get stiff and hard, and if not of good quality are apt 
to crack, unless carefully warmed before use. 

The best bags are made of unvulcanised rubber, covered 
on the outer side with twill, and on the inner side with coarse 
canvas. This rough canvas serves a double purpose it 
gives strength to the bag and also prevents the inner sides 
sticking together when the bag is empty. After a bag has 
been in use some time, the presence of this canvas makes 
itself evident by a quantity of fibrous matter which 


comes out of the jet, and which I have been gravely told 
by an ignorant operator is a deposit left by the oxygen 

The bag is furnished with a brass stop-cock, which is 
apt to get so stiff as to be very difficult to turn. For this 
reason the screw holding the plug of the tap should be 
undone frequently, and the plug touched with a little oil, 
vaseline, or tallow. This stiffness is due to free chlorine, 
which, as is explained in the chapter on oxygen making, 
is often present in that gas. The purchaser of a bag is of 
course to a great extent at the mercy of the trader, and 
many inferior bags are sold to the unwary. But a few 
inquiries among those who know what a good bag should 
consist of will soon inform the buyer where he can pur- 
chase one which is reliable in quality. Certainly too rigid 
an economy should not be exercised in this particular part 
of the lantern equipment. 

The gas-bags are made wedge-shaped so that they 
can be placed between sloping pressure boards fur- 
nished with weights. I have heard of careless operators 
who are content to trust to luck for finding suitable 
boards for their gas-bag, or bags, when they arrive at the 
scene of operations. This is, of course, a most repre- 
hensible proceeding. But should an exhibitor be so placed 
that he cannot obtain boards, a blackboard, such as can 
be found in any schoolroom, can be used for the purpose, 
provided that it is fastened by staples to the floor. It 
must also have a shelf at the other end, on its upper side, 
against which the weights can rest. This is but a make- 
shift, and one which should only be resorted to in an 


emergency. In some of my experimental lectures, where 
I require a lime-light for occasional use on the plat- 

FIG. 26. 

form, I carry with me a small bag holding only three feet 
of gas, and a special form of pressure board which I have 
designed for the purpose. It consists simply of two pieces 
of inch board, each pierced on one edge with corresponding 
centre-bit holes three-quarters of an inch in diameter- 
Into these holes fit half a dozen round rods of pine. A 
couple of pieces of wood screwed to the under edge of one 
of these pieces of board serve as a support to the twenty- 
eight-pound weight employed. The lower part of this 
skeleton pressure board is furnished with a couple of bolts 
which shoot out, and into two screw eyes, fastened to the 
floor. The whole arrangement will be rendered clear by 
the annexed sketch (fig. 26). I merely describe it here in 
the hope that it may be as useful to others as it has been 
to myself. 


For the blow-through jet only one pressure board is 
required, and perhaps a better form cannot be used than 
a couple of thin boards hinged together with a simple 
ledge, or shelf, above, also on hinges, for the reception of 
the weights. But for the mixed jet another arrangement 
is necessary. In this latter case the two gases must be 
under equal pressure. Two pairs of boards, like those 
just described, may be used side by side, but they will 
occupy a great deal of space, and a double supply of 
weights will become necessary. This last objection is, 
perhaps, more cogent than the first, for in these days of 
patent weighing machines the old-fashioned 56-pounders 
are becoming quite scarce. It is, therefore, much better 
to use a pair of boards, so constructed that they will 
embrace both bags one set of weights being all-sufficient 
for the two. A further advantage of this arrangement is 
that both bags are under the same pressure, and additional 
weights put on during performance cannot affect one bag 
to the prejudice of the other. Dangerous accidents have 
before now happened when independent pressure boards 
have been in use, from the weights having been in- 
advertently shifted from one gas, while the other has been 
left under full pressure. 

To Mr. Maiden is due the credit of having first designed 
a pair of pressure boards which would hold both bags 
under one set of weights, and the arrangement which he 
suggested is that which is now commonly adopted by 
opticians, and figured in their catalogues. I myself 
use a modified form of these pressure boards, and 
as I have given much thought to the subject before 



having them constructed, and as they answer their purpose 
most perfectly, I will describe them. 

They are what are called skeleton-boards ; that is to 
say, they consist of frames filled in with sail-cloth. This 
mode of construction saves a great amount of weight. 
The wood- work is of best pine, 1J inches thick, and is 
mortised at every joint. Referring to fig. 27, it will be 
seen that the upper frame is furnished with a couple of 


FIG. 27. 

FIG. 28. 

hinged shelves, between which the weights are placed. 
These shelves are made of hard wood, so that they will 
not readily break. The lower frame (fig. 28) has let into it 
a smaller frame, which, when the boards are not in use, is 
bolted into the main frame for travelling. But when in 
use, this lower frame is caused to fall downwards, so that 
it acts as a support for the pressure-boards, keeping them 
at the right angle. The hinges which connect the two 


frames together are of wrought iron and of very solid 
construction ; for they have to bear some amount of strain. 
It will be noticed that the sail-cloth is made in two pieces, 
with eyelet holes along the edges where they meet, so that 
by means of strong cord they can be laced up and rendered 
as tight as a drumhead. 

Between the two frames there is secured a sheet of sail- 
cloth, which is nailed down to the lower board at the 
hinged end. In the centre of its other extremity is sewn 
a flattened ring of galvanised iron. Where the sail-cloth 
is nailed to the woodwork zinc roofing nails should be 
used, for they will never rust. To the end of the 
lower frame which is farthest away from the hinges 
is nailed a strong leather strap, about six feet long, and 
when the bags are in position this strap is passed through 
the flattened ring on the midway sheet of sail-cloth, and 
then through a corresponding opening on the upper frame, 
where it is secured with a buckle. By means of this strap 
the two bags are kept in place, while the sail-cloth sheet 
between them also helps to prevent them slipping back- 

It is customary to place the hydrogen bag below and the 
oxygen one above, but I am not aware that there is any 
advantage in so doing. Certainly I have met with operators 
who prefer to reverse their positions, and seemingly without 
any disadvantage. 

The taps on the bags should have a large bore, and the 
tubes which serve to connect them with the lantern should 
also be of good size. The amount of weight on the 
bags is governed to some extent by the size of disc re- 


quired to be shown. Using a disc of from 15 to 18 feet in 
diameter the exhibitor will do well to commence when the 
bags are full with two half -hundred weights on his pressure 
boards. But when the gas has been so much used that the 
upper board gets nearly horizontal the pressure will be 
lessened, and the light will suffer to some extent. When 
this happens, the experienced operator will place another 
half-hundredweight in position, and the increased bright- 
ness of the picture will quickly show the advantage of so 

When the gas or gases are drawn direct from steel 
cylinders, or bottles, if a double or triple lantern is in 
use, some form of regulator must be employed. The first 
introduced, and perhaps the most perfect, is that patented 
by Messrs. Oakley & Beard. 

Before proceeding to describe this important new de- 
parture in lantern working, it may be as well to point out 
one or two difficulties which are incidental to the ordinary 
method of storing the gases required in india-rubber bags. 
So far as the writer knows, one of these difficulties has 
never been recognised in print. This difficulty is com- 
prised in the fact that any kind of gas, if kept in an india- 
rubber bag, quickly deteriorates. By the phenomenon 
known by the term endosmose, two gases separated by a 
porous diaphragm will effect a mutual exchange. Take 
the case of an ordinary india-rubber tube used. for a table 
lamp or gas stove. How quickly it begins to smell. 
This is nothing else but the gas escaping through the 
india-rubber, and carrying on an exchange with that other 
gas the air which is outside. It would be interesting 


to know how quickly this exchange takes place in the case 
of a bag of oxygen; but, as an experienced worker, I 
have no hesitation in saying that there is a marked 
deterioration in the quality of the lime-light, if the oxygen 
gas used has been kept for only 24 hours in a bag 
instead of being freshly made. The same rule will 
apply to the hydrogen gas in a greater degree, for the 
hydrogen passes through a porous diaphragm far more 
rapidly than can oxygen. But, in practice, the H bag is 
filled from the nearest gas-tap immediately before it is 
wanted. (Mr. Fletcher, of Warrington, has patented a 
method of preventing the smell of gas-tubes, by inserting 
a partition of tinfoil between the two layers of india-rubber 
which compose the tube. This foil stops the smell, by 
stopping endosinose. The same principle might, of course,, 
be applied to gas-bags. Here is a hint for manufacturers.) 
Other objections to the use of gas-bags are found in their 
initial expense, and the necessity for constant renewal, 
their bulk, and their liability to mechanical injury. In 
spite of these defects, I have always preferred to use gas 
in bags, rather than gas compressed in cylinders. My 
reasons for this choice I will now give. 

If the gases are compressed in cylinders, there is a 
great saving in trouble, as well as in bulk of apparatus ; 
but I have hitherto set my face against them for the 
following reasons: 1. The pressure is so great, that the 
india-rubber tubes are apt to blow off ; and, if tied on, may 
burst. 2. The light cannot be regulated at the jets and 
by the taps provided for that purpose, but the taps must 
be turned fully on, and the outrush of gas roughly 



regulated a very difficult matter by the screw plug on 
the nozzles of the bottles. 3. The operator at the lantern, 
even if he succeed in thus procuring the delivery of the 
proper amount of oxygen and hydrogen respectively, must 
stoop down to do so, and, for the time, neglect other duties. 
4. The pressure is constant ; and, therefore, if a double or 
treble light is suddenly wanted as in the case of biunial 
and triple lanterns the amount of gas measured out for one 
light, must serve for two or three, as the case may be 
and all suffer. 5. As the bottles gradually empty, the 
pressure sinks ; and, therefore, the screw-plugs have to be 
opened several times during an evening's work. Every 
time this becomes necessary, there is a likely chance of too 
much being turned on, and the tubes being blown off. It 
is, therefore, seen that, although bags are troublesome, 
bottles possess many disadvantages which would make any 
careful operator pause before he adopted them. These 
disadvantages, however, entirely disappear when the 
bottles are used with regulators. 

The action of the regulator can be understood without 
much difficulty by reference to the annexed sectional 
diagram, fig. 28. The screw-thread d* at the bottom of the 
drawing, is where the casting D fits upou the bottle of 
compressed gas ; d l is the delivery tube, governed by the 
stop-cock d 2 . B is a base-plate supporting the most im- 
portant part of the apparatus, and E E standing upon it 
is merely a casing to protect the enclosed part from injury. 
A A are bellows made of the finest rubber, and of a form 
not unlike the bellows of a camera, only that it is circular. 
The top of the bellows is heavily weighted, jso that its 



natural tendency is to remain compressed. This top is 
furnished with a collar O l , having a screw-thread in which 
the screw pillar F can easily turn. It will be noticed 
that the thread of the screw is coarse, so we may call 
it an Archimedean screw. At its lower part is a fine, and 


Fig. 28. 

therefore slow-motion screw, which works in the collar c. 
Now, let us see how beautifully this double-screw motion is 
applied to regulating the delivery of the highly-compressed 
gas. As soon as the gas emerges from the bottle it passes 


between the space which is open between the valve/* and 
the valve seat d. It then rushes into the bellows above, 
which become gradually raised by its pressure. As the 
bellows rise the screw pillar F is quickly turned in its 
socket, and gives a slow motion to the screw below. The 
effect of this movement is to bring the valve f down on its 
seat d) and the supply of gas is cut off. But in practice 
the gas will be drawn off from the delivery tube d l so 
that the bellows will soon be compressed once more. As 
the bellows move downwards, the screw F acts in the reverse 
manner, so that the valve F is now raised, and a fresh 
supply of gas enters the bellows. In this way the bellows 
are constantly rising and falling. If but one lime-light is 
in use, and the delivery of the gas is therefore regular, 
the bellows will be almost stationary, for they will auto- 
matically adjust the valve F, so that just enough gas, and 
no more, will pass through the opening. But if two or 
three lights are in use, and sometimes only one, and per- 
haps immediately afterwards all three are requisitioned, 
then the little bellows will have a more lively time of it. 
In both cases the regulator will deliver the quantity of 
gas which happens at the moment to be required. 

Some time ago I contributed to The Camera, an illus- 
trated article showing how ? by the use of a small gas-bag, 
A, the outflow of gas from a cylinder might be regulated. 
The bag was in this case made to raise a lever as it 
filled, thus cutting off the gas supply from the bottle, until 
the hag was partially emptied, when the action was repeated. 
Shortly after the publication of this article a self-acting 
valve on the same principle was introduced. This valve 


is shown at fig. 29. A is the loose nut by which it is 
attached to the gas-bottle ; B, the 
valve proper, which is governed 
by the spring lever D. The 
tendency of this spring is to keep 
the bag shut, and when in that 
position the tap is open. The 
gas pressure, however, quickly 
inflates the bag, and turns off the 
gas supply. The delivery pipe, 
E, is connected with the lantern. 
The. apparatus is small and com- 
pact, and works well. 

It may be noted here, that there is a distinct gain in 
using pure hydrogen, instead of the carbureted gas 
from the main, although its employment undoubtedly 
leads to extra trouble and ex- 
pense. The most convenient 
way of making this gas in small 
quantities is by treating scrap 
zinc with dilute acid. A con- 
venient apparatus is that shown 
in the diagram, fig. 30. It was 
devised some years ago by Mr. 
Pumphrey, and published in one 
of the Photographic Annuals. 
It consists of a copper container, 
in which is an inverted box with 
a delivery tube and tap attached 
to it for drawing off the gas as 
it is generated. This inner box 

Fig. 30. 


has a removable perforated shelf fitted to it, and the box 
itself is so arranged that it can be wedged tightly in its 
place. The shelf is to hold the necessary supply of 
scrap zinc, and as . the acidulated water attacks the 
metal, hydrogen is rapidly given off, until the water is 
forced by the pressure of the gas below the shelf, and 
the action ceases. It is again renewed when gas is 
drawn off from the tap, for then the water again rises 
to the zinc, and a fresh supply is generated. This 
apparatus is clearly a modification of the Dobereiner 
lamp, in which the gas generated in this manner impinges 
upon and renders red-hot a -pellet of spongy platinum. 
At a recent lantern exhibition at the Crystal Palace, where 
a 30-foot screen was used, pure hydrogen from a bottle 
fed the lime-light. On one occasion ordinary coal-gas was 
substituted, with a loss of light which was estimated by 
those well qualified to form a judgment, at no less than 
25 per cent. 



[HE lime-light was discovered about the year 1826 
by Lieut. Drummond, R.E., during the progress 
of the Ordnance of Ireland Survey, when the 
want of some method of signalling between distant stations 
was much felt. As originally constructed, Drummond's 
lamp was very different to the convenient forms of lime jet 
now in use. It consisted of a blow-pipe, which impinged 
upon a ball of lime about as big as a marble. This lime 
ball did not last more than half an hour, but when spent 
another took its place automatically. The lime ball was 
placed in the focus of a parabolic silvered-copper reflector. 
With this apparatus, the light was visible from Antrim in 
Ireland, to Ben Lomond in Scotland, a distance of ninety- 
five miles as the crow flies. Upon another occasion, the 
light from the Drummond lamp was distinguishable at a 
distance of one hundred and twelve miles. 

When manufactured limes cannot be obtained, a piece 
of limestone fresh from the kiln can be sawn roughly to 


the cylindrical form, and rubbsd down with a file ; or a 
piece of good hard chalk will serve, if there is nothing 
better at hand. The following mixture has been recom- 
mended as one from which a hard substance can be 
moulded which will take the place of the usual lime 
cylinder : 

Precipitated Chalk 4 parts. 

Heavy Magnesia, Carbonate 1 part. 

Mix to paste with gum-water, and mould to form. 

Of late years some new limes have been introduced, with 
the trade-mark "Excelsior." These will do admirably for 
the blow -through jet, but will not (at any rate in my 
hands) withstand the attack of a powerful mixed jet. I 
have always regretted that I cannot use them, for they are 
uniform in size, are accurately turned and bored, and are 
packed in a. very convenient manner. A good hard 
material which will last for several hours, and which is not 
affected by damp, is a thing that is much wanted for lime- 
light working. The following extract from Lieut. Drum- 
mond's paper in the Philosophical Transactions, 1826, is 
interesting, as showing that the discoverer of the lime-light, 
made trials of various substances, but found lime to be the 
best : 

" The results of several trials made at the commencement, 
gave for 

Lime 37 times 

Zirconia 31 times 

Magnesia 16 times 

the intensity of an Argand burner. The oxide of zinc was 


also tried ; but besides wasting away rapidly, it proved 
inferior even to magnesia. 

" Of these substances, and also of their compounds with 
one another, lime appearing to possess a decided superiority, 
my subsequent experiments were confined to it alone, and 
by a more perfect adjustment of the apparatus, by bringing 
the maximum heat, which is confined within narrow 
limits, exactly to the surface of the lime ball, and by using 
smaller balls than those employed in the early experiments, 
a very material increase of light has been obtained. The 
mean of ten experiments, made lately with every pre- 
caution, gives for the light emitted by lime, when exposed 
to this intense heat, 83 times the intensity of the brightest 
part of the flame of an Argand burner of the best construc- 
tion, and supplied with the finest oil. The lime from chalk, 
and such as is known at the London wharfs by the name of 
flame lime, appears to b3 more brilliant than any that has 
been tried. When well-burned Carrara marble is made 
into a paste with water, and gradually dried, it appears to 
be nearly equal to the preceding ; when strongly com- 
pressed, or very porous, it is inferior." 

The best limes to be obtained are of the kind known as 
"hard," or "Nottingham limes." These last better than 
any others that I know of. They are sold in tin boxes 
holding one dozen each, and are packed in powdered lime, 
kept as far as possible from the air. Let it be remembered 
that these limes will be spoiled by exposure to damp air. 
By such exposure they swell to double their normal size, 
will break the strongest box in which they are confined, 
and will, finally, fall to powder. In other words, they are 


made of quick lime, and moisture will slake them. Lime 
cylinders are difficult things to keep, for damp air will get 
to them in spite of ordinary precautions. I have tried to 
preserve them with partial success by dipping each 
cylinder separately into a solution of indiarubber in ben- 
zole or chloroform, which forms a skin upon its surface. 
An American writer publishes a better plan. He melts 
some solid paraffin or bees' wax in a metallic vessel, 
exercising care that the heat is just enough to render 
the substance liquid and no more. He then dips each 
cylinder into the wax half way, allows it to cool, and then 
holding it by its waxed end, dips the other half. This 
coating, he says, quite excludes the air, and the limes may 
be rolled in paper and packed away until 'wanted for use. 
The coating is readily peeled off when the lime is required 
for the lantern, provided that the heat employed in melting 
the wax was not too high when the cylinders were dipped. 
Each lime is cylindrical, and about one inch and a half in 
length, with a central hole for the reception of the pin 
upon the jet. This hole should be carefully freed of 
powdered lime, by running a match through it, after 
which the cylinder can be placed upon its pin, where for 
the present we will leave it. 

As already indicated, the most commonly used form of lime 
jet is the safety, or blow-through kind. If the jet be a 
properly-constructed one, it will well illuminate a picture 
15 feet in diameter. In this jet the hydrogen is sup- 
plied from the nearest household source, by a connecting 
tube of india-rubber. Herein lies, perhaps, its only dis- 
advantage. In an ordinary house the connexion is an 


easy matter, but in large halls, which are now commonly 
lighted by one or two sunlights high overhead, the 
operator finds himself in a serious difficulty. In this jet 
the two gases do not mix until they reach the point of 
combustion, and for this reason the apparatus is dis- 
tinguished by the word " safety." For hydrogen and 
oxyen, when mixed together, form an explosive vapour of 
most terrible power, and one which is most difficult to 
control. If any one should wish to prove this, let him fill 
a soda-water bottle with the gases over a pneumatic trough 
in the proportions of two volumes of hydrogen to one of 
oxygen. Then close the bottle with a well-greased cork, 
and, after wrapping it in a towel in case of fracture, take 
out the cork, and put the mouth of the bottle in front of a 
candle flame. The report caused by the explosion of the 
gases will be quite equal to a heavily-charged fowling- 
piece. But when the two gases are used in conjunction 
with the safety-jet there is no risk of explosion, for no 
mixture takes place until the gases meet on the lime 
cylinder. I know that accidents have happened when 
this jet has been in use, but they are traceable to im- 
proper use of the apparatus. A case of this kind came 
under my notice quite lately. An optician had employed 
a new hand to see after the making of the oxygen gas and 
filling the bag with the same. This individual was, after 
a time, left to his own devices, and finding, upon one 
occasion, that the bag was not full, he attached it to the 
nearest gas-bracket until it was properly distended. This 
bag was used in public the same evening, and a few 
minutes after bhe proceedings commenced it blew up, and, 


besides wrecking the lantern, smashed all the windows in 
the hall. The cause of the disaster leaked out afterwards. 

But with proper care this jet is perfectly safe, and 
one which I have used scores of times for purposes of 
demonstration in crowded school-rooms. As the bulk of 
my readers are more likely to adopt this form of limelight 
than any other, I will give directions for working with it 
which will at once show its simplicity. We will suppose, 
in order to make the matter clearer, that the operator has 
a single lantern fitted with this form of jet. 

Beyond the mere lantern and its belongings, there will 
be required some india-rubber tubing, a box of limes, and 
a bag or bottle of gas. The best rubber tubing is the red 
variety ; but it is expensive. It will, therefore, be found 
economical to adopt a plan which I myself have practised 
with advantage. Two lengths of tubing are required, one 
for each of the gases employed. A 6-foot length will be 
sufficient to connect the side of the jet with the iron 
bottle or bag ; but the length of the other piece of tubing, 
which is to connect the H side of the jet with the nearest 
house gas-burner, is obviously dependent upon the distance 
of that supply from the place where the lantern is being 
exhibited. If the nearest tap is in another room, it is best 
to use a length of compo. (lead) gas-pipe, which is absurdly 
cheap. Upon one occasion I remember drawing the gas 
from another house by such a means of communication, 
the pipe passing through two windows. But it is only 
upon rare occasions that such a proceeding is necessary, 
and the worker is generally able to find a source of gas- 
supply ready to his hand. When such is the case, I 


recommend the employment of two different kinds of 
tubing. There is a hard black kind, made, I fancy, in 
France, but easily procurable in this country, which wears 
extremely well, far better, indeed, than the ordinary grey 
kind. It is cheap as well as good. The only part where 
it seems to deteriorate is the end, where it is being 
constantly fitted on to the metal jet. This gets soft and 
rough after some time, a failing which is easily remedied 
by judicious amputation. Use for each gas a sufficient 
length of this black tubing, and firmly attach to the end 
of each piece a short length of the more elastic red tubing, 
by which connexion with the bottle and house gas respec- 
tively can be easily made. In joining the two kinds of 
tubing together, use a couple of inches of lead pipe as a 
connecting link between them. First draw the black 
tubing half way over the lead, and then, if possible, allow 
the red tube to cover both, securing the whole with 
string. , - 

Having all these things ready, the H tube fastened to 
the nearest gas supply, and the tube to the bottle or bag, 
we can proceed to work. Let the lime-pin be so adjusted 
that the lime is about 1-1 6th of an inch from the nozzle of 
the jet. Then turn on the tap marked H, and light the 
jet. Turn down the gas until the flame is about one 
inch high, and let matters thus remain for five minutes, to 
give the lime time to warm through. Without this pre- 
caution, and if the oxygen is turned on at once, the lime 
is apt to split up from the sudden heat. 

After this five minutes' rest, you may attend to the 
oxygen supply. If the gas is supplied from a bottle or 


cylinder first turn the tap of the jet full on, and let it 
remain so. This is a most important point, and for the 
following reason : the supply of oxygen must be regulated 
only from the tap on the bottle, for the pressure of gas is 
so great that if we turn on the bottle tap and then attempt 
to check its flow by moving the tap jet, the connecting 
rubber tube will be blown off or possibly split up. There 
is another advantage in keeping the hydrogen jet burning 
for some time before the lantern is used. It warms the 
glasses, and prevents that deposit of moisture upon them 
which is otherwise always more or less apparent, especially 
in a crowded room. Turn the H tap until there is a good 
big flame from the jet, and now very, very gradually turn 
the lever tap of the bottle. If you do this too quickly, the 
sudden mixture of and H at the jet causes the light 
to go out with an unpleasant crack. There is really no 
danger, but the noise frightens nervous people, who are 
prone to associate with lanterns generally the idea of being 
blown skyward. The regulation of the two gases is a 
matter which is soon learned by experience, and is governed 
by the appearance of the disc of light obtained on the sheet. 
Move the two taps until the best effect is obtained ; the 
knack of doing so is very soon learned. 

Having seen that the gas jet is burning well and quietly, 
which is one sign that all is at it should be, the next thing 
is to see that the light is perfectly central with the optical 
system. See that the tray upon which the jet is fixed is 
withdrawn so as to leave a space of about 4 inches 
between the light and the condensing lens. Raise or lower 
the jet on its supporting rod, and move it from left to 
right until the flare of light seen upon the sheet is as 


central as possible. When this is the case, tighten the screw 
or screws (and two are better than one) which hold the jet 
on the rod, so as to clamp it firmly in position. Now press 
forward the tray, so that the light approaches the condenser, 
and this will cause the sheet to become equally illuminated 
with a sharply -defined margin all round. Now place a 
slide on the stage of the lantern, and focus it as sharply as 
possible. The best way to do this is to set the focussing- 
screw so that it is at its middle position, then focus by 
sliding in and out the flange into which the objective is 
screwed. Get roughly the best focus which you can obtain 
by this means, and then give a finishing touch by means of 
the focussing-screw. 

If a double or biunial lantern be employed, the necessary 
operations will be rather more complicated, for here we shall 
have two lights, and two optical systems to control instead 
of one. But, when once understood, the working of a double 
lantern is both simple and easy, so much so that on many 
occasions when a good assistant was not forthcoming I have 
worked the lantern myself and lectured at the same time. 
The two lanterns are connected by means of a dissolving tap, 
such as that shown in fig. 3, which is a very good pattern. 
This tap is so arranged that when the lever is upright both 
lanterns have their full supply of the gases ; when the 
lever is turned over towards the left-hand side, the lower 
lantern only is provided for, whilst when in the reverse 
direction the upper one is supplied with gas. The original 
plan for dissolving was to move a couple of serrated 
screens to and fro in front of the lenses, both jets 
continuing burning during the entire exhibition. The 
more modern method of cutting off the gas supply from 


each lantern alternately has the great merit of saving 
nearly half the gas bill. It will be noticed in the cut of 
the dissolving tap that it is furnished with two small stop 

cocks, which are fixed on vertical tubes near its centre. 
These tubes are by-passes which allow a small quantity 
of gas to pass to each burner, although the lever has 
shut off the main supply. The necessity for this arrange- 
ment is obvious ; without it the lantern not in actual use 
would be totally extinguished. In using the blow -through 
form of jet :both by-passes, must be employed, but with 
the ;mixed jet the hydrogen by-pass only is necessary. 
The first thing to be done in operating with a double 
lantern is to light the hydrogen in both lanterns, and to so 
adjust the by-pass that it will admit just enough gas to 
the lantern not in use to give a flame about half an inch 
high. When the blow -through jet is used the correspond- 
ing oxygen tap must be manipulated to furnish just enough 
of that gas to tinge the hydrogen flame. If this precaution 


be not taken, the sudden influx of oxygen to the burner, 
when the dissolving lever is turned, will almost infallibly 
cause the flame to snap out with a sharp crack. 

The mixed jet is as easily worked as the safety form and 
despite the confidence-inspiring name of the latter is, 
in my opinion, quite as safe in careful hands. In some 
forms of mixed jets pumice-stone chambers, receptacles 
charged with discs of wire-gauze, and other arrangements 
which are supposed to prevent the flame passing back 
through the tubes, form part of the design. I look upon 
such contrivances as mere obstacles to the free passage of 
the gas \ and, although some of my jets were originally 
provided with them, I did away with them as quickly as 

The dissolver for a triple lantern is naturally more com- 
plicated ; but taps have been devised which are so arranged 

FIG. 33. 

that any one of the three lanterns can be put in or out of 
action at will. Such a tap is shown at fig. 33. Another 



pattern of very compact form is illustrated at fig. 34. In 
this case the by-passes are governed by taps which are 
adjusted by the operator with a screw-driver. This seems 
to be a good arrangement, as there is no chance of 
accidental turning off or on by a careless touch, as may 
happen when the by-pass taps are exposed. 

FIG. 34. 

There are one or two methods of manufacturing oxygen 
gas for the limelight as fast as it is used, and although, 
for reasons which I shall presently give, I cannot recom- 
mend such a procedure, the methods are ingenious enough 
to warrant notice. In Chadwick's apparatus there is an 
iron gas-holder, which forms the support of the lantern. 
Associated with it is a special form of retort heated by a 
Bunsen burner, and charged with chlorate of potash and 
manganese made up into a cake previously. The operator 
starts with a full gas-holder, and at the end of perhaps 
fifteen minutes, when it is nearly empty, lights the Bun- 
sen burner, and in a few minutes enough gas is generated 
to fill it once more. The retort is now charged with a 
fresh cake of mixture ready for once more filling the gas- 
holder as it sinks. 


Another plan was originated some time ago by Mr, 
Beseler, of New York, and published by him in one of the 
American journals. In this case the mixed chemicals are 
placed in a metal tube, with a Bunsen burner beneath it. 
As the gas is generated it fills a small gasholder, which 
supplies the lantern. Only one part of the tube at a time 
is subjected to heat, so that when a fresh supply of oxygen 
is wanted, all that is necessary is to shift the Bunsen 
burner to another part of the tube, and the gasholder is 
replenished. This latter plan is more simple than Chad- 
wick's ; but I object to both, unless it be for experimental 
work at home, on two broad grounds. One is, that the 
blow-through jet can only be used in conjunction with 
such an apparatus, and the other is, that a lantern operator 
has quite enough to do in attending to his burners and 
changing the pictures without being burdened with the 
constant anxiety of seeing to the gas supply. 

Of late years much has been heard about the so-called 
ether-oxygen or ethoxo limelight, so called because the 
vapour of sulphuric ether is used in lieu of the ordinary 
hydrogen, or coal-gas. I have tried this light, and, while 
admiring its brilliance, which is quite equal to any form 
of limelight which I have seen, I am very doubtful as to 
its safety. I have no doubt that it can be so arranged as 
to work with safety ; but several explosions which have 
occurred with it show very conclusively and unpleasantly 
that that time has not yet arrived. With the tempting 
advantages of extreme portability and brilliant light 
which this or any other system may offer, I hold that it is 
a positive duty to eschew it until it is known by further 



experience to be absolutely innocuous. Some may say, 
" Oh, there is no real danger ; the worst that can happen 
is one of the tubes blowing off with a bang ! " But this 
apparently harmless "bang" may cause a panic in a 
public hall, which may lead, possibly, to fatal results. So, 
for the present, at any rate, I shall do without the ether 
light, while, at the same time I shall look forward to its 
gradual perfection with the greatest interest. It is only 
fair to state that this light is much used in America, 
its greatest champion being Mr. Ives, who recently con- 
tributed a paper on the subject to the Franklin Institute. 
Mr. Ives is such a good worker that his words carry weight 
with them. I quote the following remarks from his 
paper : 

" Notwithstanding the great success of this means for 
producing the limelight, and the important advantages 
which it offers, I have always recognised in it certain 
minor faults, which I hoped to overcome in course of time, 
and my object in preparing this paper has been to call 
attention to some recent improvements I have made, which 
I believe will greatly extend the use of the light, and 
increase its popularity. The first improvement is in the 
construction of the saturator, which is reduced in size, yet 
increased in effectiveness. The second is in the use of 
petroleum ether (rhigolene), which gives the same light as 
sulphuric ether, but vaporises at a lower temperature, costs 
much less, and contains neither alcohol nor water to accu- 
mulate in the saturator. 

"My improved saturator is in the form of a single 
metallic tube, 2 inches in diameter and 13 inches long, 


with a handle at the middle and a stop-cock projecting up- 
ward at each end. A neck, like that of a bottle, projects 
from the screw cap at the end, and is closed with a cork 
for convenience in filling. The passage for oxygen is over 
20 inches long, in the form of a zig-zag channel through 
the upper surface of the roll of porous material, and 
secures complete saturation of the gas with vapour. The 
saturator can be filled from a bottle in one minute, and is 
ready for use at once, or may be kept filled for any length 
of time. Petroleum ether costs only thirty cents a pound, 
which is less than half the price of sulphuric ether ; it also 
vaporises at a lower temperature, so that the light can be 
used successfully even in a very cold room, and it has 
other advantages. It will supply a pair of lanterns con- 
nected by dissolving key, for two hours continuously. It 
should be stored in a cool place and kept tightly corked. 
It is also necessary, when using it with oxygen from a 
cylinder, to use a valve that can be opened very slowly, 
because a very small amount of oxygen passing the satu- 
rator will produce a very large flame at the jet. The 
Shaw valve, manufactured by Mr. Shaw, a member of this 
Institute, fulfils the requirements, and is already largely 
used in this city. Some special instruction for the manage- 
ment of the light in hot weather may also be called for. 

" In conclusion, I give it as my opinion that this im- 
proved means for supplying the hydrogen element is so 
much simpler and more convenient than any other, that it 
cannot fail to entirely supersede the use of hydrogen and 
coal-gas, when its merits shall have become generally 
known and appreciated." 



this head comes the sheet, hung in 
the required position by supporting cords, and 
screens fixed on built-up frames. 
First, as to the simple sheet. A badly-hung sheet is 
an abomination. It should be so hung that there is a cer- 
tain pall upon it from the centre to the edges all round, 
and this may b3 brought about by following the directions 
now given. The sheet may be made of either linen 
or cotton. I prefer the latter, because it is cheaper, and 
more opaque, and we shall presently see that opacity car- 
ries with it certain advantages. . If the sheet is of such a 
size that it must be joined (that is to say, if it be more 
than about 10 feet square), the necessary seams should lie 
horizontally, not vertically. A sheet in which the seams 
are vertical, is liable to hang in festoon-like folds ; but if the 
seams be horizontal, it will hang straight, so long as its top 
edge is properly secured. The sheet should have along 
this edge a broad hem, in which is run a strong cord- 
This cord should be firmly fastened to the corners of the 


sheet, and in such a way that when it is stretched, the 
material of which the sheet is made will not pucker. At each 
end of this cord there should be a loop made by doubling 
it over, and wrapping it round with waxed thread. 
Along each side of the sheet should be placed, at intervals 
of about eighteen inches, galvanized iron rings, or brass 
curtain rings will answer the purpose. The bottom of the 
sheet may be left free. 

A screen of this description will require no fittings to 
hang it in position, beyond a couple of screw-eyes placed 
so far apart that the sheet will easily go between them ; 
and which should be inserted in the cornice or roof of the 
exhibition-room, with two more eyes placed immediately 
underneath the top ones, and screwed into the floor. Next 
are required two strong but thin cords ; and it is best at 
the outset to procure these of the best quality possible, for 
upon their strength the sheet entirely depends. Eich cord 
should be fitted at one end with a swivel and clip like that 
upon a dog's chain. 

Having made these preparations the hanging of 'even a 
large sheet will be comparatively easy. First, let the cords 
be run through the fixed screw-eyes in the roof or upper 
pirt of the wall ; one cord through each eye, and so inserted 
that the clips on the cords are inside, i.e., facing each 
other. Next clip the sheet to the cords by the loops pro- 
vided at the top corners, as already described. The sheet 
can now be pulled up bodily, preferably by two persons, 
one at each cord. Next place the free ends of the cords 
through the screw-eyes in the floor, and stretching the sheet 
as tightly as possible, secure each by a simple knot. 



We shall now see the advantage of the eyelet-holes or 
rings at the sides of the sheet. Fastening a piece of 
string to the top eyelet-hole at one side, and this is better 
done before the sheet is pulled into position, allow that 
string to embrace the supporting cord, next let it pass 
through the nearest eyelet-hole, then again round the cord, 
and so on until the bottom of the sheet is reached. By this 
lacing method the sheet can be rendered almost as flat as a 
board, and presents the best possible kind of surface so far 
as a sheet can give it for showing lantern pictures well. 

Some little judgment must be exercised as to the best 
position for the upper screw-eyes. Of course, in practice, 
difficulties are apt to occur. The best position may be one 
which the ladder available will not reach. Again, it is 
often the case that screw-eyes may be found already 
in position, and the owners of public halls have a righteous 

Fig. 35. A B 

objection to holes being made, even to the tiny ones 
necessary for fresh screw-eyes. In such a case the 



exhibitor must content himself with existing arrangements. 
But supposing that he has a free will in the matter, he 
must exercise his judgment with regard to the size of the 
hall, and the best position for hanging a sheet. For in- 
stance, in a hall with a pointed roof, the position A (see 
figure 35) would be preferable to position B. In some 
halls, again, the walls may be so far apart that the sheet 
will, when hung in the manner described, drop consider- 
ably by its own weight, so that, although the screw-eyes 
may be 20 feet from the ground, the top edge of the sheet 
will be only 14 or 15 feet above the floor. The best 
way of obviating this is by the use of two wooden struts, 
or supports, placed as shown in figure 36. In this dia- 

FIG. 36. 

gram the dotted lines indicate the position which the sheet 
would occupy without this help. 

The material of which the screen or sheet is made is of 
far more importance than would be thought by an inexperi- 
enced worker. A careful artist knows that a good picture 
cannot be produced on crumpled or dirty paper ; and the 
lantern exhibitor should be quite as careful to provide for 
his pictures an unblemished and even surface. Un- 


doubtedly the best thing of all is a simple white-washed 
wall. Why should this be so ? Let me endeavour to 
explain the matter in a few words. 

Suppose that we go behind an ordinary linen or cotton 
sheet, while lantern pictures are being thrown in front and 
upon it. We not only see the picture distinctly through 
the sheet, but there is enough light round about us to enable 
small print to be read with ease. At least such is the case 
with the lime-light, and in a minor degree with the oil 
lantern. Now all this light means so much deducted from 
the light available from the lantern, and which, therefore, 
is completely lost to the spectators in front. From an 
opaque wall, on the other hand, the light is nearly all reflected 
to the spectators' eyes ; and although no doubt some must 
be absorbed, we know that none is actually transmitted 
through the screen, and utterly wasted, as in the case of a 
semi-opaque sheet. We might compare the two cases, to a 
vessel of water with a porous bottom, which will, of course, 
allow a large portion of the liquid to dribble through and 
be lost ; as against a vessel with a solid bottom which will 
hold water without any wasteful transmission. But a 
white-washed wall is not often met with in a lecture-hall, 
and the best substitute is a canvas sheet rendered opaque 
with white-wash. Such a sheet is portable up to a certain 
size ; and if intended for use as a fixture in any one hall, 
can be made up to any size, within reasonable limits. 
Witness the scenes on rollers at our large theatres and opera 
houses, the basis of which is simply whitened canvas. Such 
a plan was adopted at the late Polytechnic Institution, where 
the screen measured no less than 26 feet across. 


There is a further advantage connected with using a 
sheet of this description, which is that when, not in actual 
use it can be rolled up, and will keep perfectly clean for 
many years. When soiled, a fresh coat of white-wash can 
be given to it with little trouble and expense. For home 
use a screen of this nature is to be greatly recommended. 
Let me now describe the method by which such a surface 
can be prepared, and the best way of hanging it in position. 
The following detailed directions are quoted from an article 
upon the subject which I wrote some time back : 

Having decided upon the dimensions of the screen, 
which, of course, must be governed by the size of the 
room in which it is to be hung, we must first of all have a 
frame made upon which the material can be stretched 
whilst being painted. Any kind of close-textured material 
will answer our purpose, good unbleached calico being as 
suitable as anything else. The frame should be strong, 
for as soon as the sheet is wetted it shrinks, and is apt to 
pull an ill-constructed frame all askew. The calico, if 
joined, should be neatly sewn, and so tacked on the frame 
that the seam, or seams will lie horizontally. The sheet 
must be nailed on the frame with tacks, and this appa- 
rently simple work must be done in a certain way, or 
it will be pulled into creases. The four corners must 
be first secured, and afterwards the sides may be nailed 
down, one side being completely nailed before another is 
begun. By this means the sheet will, when done, present 
one even surface. This done, it must receive a coat- 
ing of size. The best double size should be used, and 
should be melted in a suitable vessel with its own weight 


of water. The size while on the fire should be watched 
and occasionally stirred, but should not be allowed to boil. 
When melted, this size is well brushed into the calico, and 
allowed to dry. It will then be ready to receive its 
coating of white paint. This consists of whiting which 
has been soaked in water until it assumes the appearance 
of thick white mud. To this strong melted size must be 
added until the mixture is of the consistence of cream. 
It can be left now for some hours until it has become 
perfectly cold. At the end of that time it should have 
the appearance of very weak jelly, a jelly which can be 
easily broken up by the paint brush. 

The frame being placed upright and properly secured, 
the workman commences at the top, working the well- 
charged brush up and down, and then horizontally, so as 
to avoid leaving any lines upon the surface, until it is all 
covered. If the sheet be unusually rough in texture, it 
will benefit by another cqat when the first is dry. 

When this painting operation is finished the nails must 
be drawn from the frame, and the sheet must be tacked 
on to a roller. This roller may be hung like a window- 
blind at the top of the room, and governed by a cord in 
the familiar manner. But if it is of large size, say 12 
feet across or more, the roller is best placed at the bottom 
of the sheet, and made to roll up by cords upon its pro- 
jecting ends, and pulleys above like the drop scene at a 

It has often struck me as a deplorable oversight that 
halls where lantern lectures are of constant occurrence, 
are not fitted with permanent roll-up screens of this kind. 


T know most of the lecture-halls in the kingdom, but I am 
not aware of a single one where this arrangement exists. 
The lecturer who visits these places is responsible for 
bringing his own screen, and his assistant must fit it up, 
an operation which is sometimes, owing to the structure 
of the hall, very troublesome and difficult. A permanent 
rolled-up screen would obviate all this difficulty, and would 
add greatly, for the reasons already given, to the success of 
the exhibition. I can only suppose that this is one of those 
matters which comes under the head of everybody's 
business, and therefore nobody attends to it, or seeks to 
remedy what I feel is a mistake. 

We will next consider the method of hanging a sheet on 
a portable frame. Some lecturers adopt this plan, and if 
they are not afraid of adding to their luggage a huge 
bundle of sticks, they certainly have the advantage of 
being independent of ladders, staples, and all the things 
necessary for hanging a sheet in the ordinary way. There 
are several descriptions of frames made for this purpose, 
which are sold by dealers ; some are good, and some 
are very much the reverse, giving much more trouble 
than they are worth. Perhaps the best form of frame is 
that which is made of round pine sticks, about 4 or 5 feet 
long, like broom-sticks, and which fit to one another, 
fishing-rod fashion, by means of brass sockets. The 
corners of the frame are represented by sockets mitred, and 
brazed together, see fig. 37. Such a frame as this is easily 
put up. First of all the top pieces are socketed together, 
and furnished with their corner pieces and one length of 
the wooden rods. The side pieces are next placed in their 



proper sockets, and the top portion of the sheet is tied on by 
tapes. It is reared up a little higher by the addition of two 
more side pieces ; and as this building-up gradually goes on 
the sides of the sheet are secured by tapes to the frame. The 

Fig, 37. 

bottom pieces are finally attached a.nd the frame is com- 
plete. If there is room enough this operation of mounting 
the sheet on its frame is best performed when both are 
lying flat on the floor, otherwise it must be done by 
gradually building up the frame while it is in a vertical 
position. At each top corner should be fastened guy 
ropes, and these can be secured to staples screwed into 
the floor. 

One advantage of a frame of the above description is 
that, when, from the nature o'f the hall, it must be erected 
on a platform at a higher level than that of the lantern, 
the whole screen can be made to incline forwards, so as 
to bring its surface square with the lens. With a strictly 
vertical sheet the picture would, under such circumstances, 
be thrown out of shape and out of focus. 

Whatever wood may be chosen for the material of the 


frame, it should be strong ; for if the sheet is tightly- 
stretched, as it ought to be, there will be a very heavy 
strain upon its support. Perhaps the best wood for the 
purpose is bamboo, which combines the qualities of 
extreme lightness with great strength. I believe that 
bamboo frames can now be obtained commercially. 

The rule for finding the correct distance between lantern 
and sheet is to add one to the number of times enlargement 
required, and multiply by the equivalent focus of the lens 
used. If, for instance, a slide measures 3 inches, and it is 
desired to cover a screen 10 feet across, the scale of 
enlargement is 40 times : and 41 times the equivalent 
focus of the lens gives the required distance between lens 
and screen. 

In order to find the equivalent focus of a lens, it is con- 
venient, in the absence of special apparatus, to proceed as 
follows : Focus upon a white surface an image of the 
Sun or other distant object, taking care to place the lens 
axis as nearly as possible in line with the object, and 
perpendicular to the surface receiving the image. When 
the image is sharply focussed, measure carefully the dis- 
tance between it and the nearest surface of the lens. 
Repeat this operation with the lens reversed, and measure 
the distance to the same surface as before ; in this case, 
the surface furthest away. The average of the two 
measurements thus obtained is approximately the 
equivalent focus of the lens. 

I am indebted to Mr, Taylor, of Leicester, for the fol- 
lowing useful table : 





























































15' 5" 



































































601' " 






32' 11" 








































































105 5" 
















it became possible to use photography in 
conjunction with the lantern, what are called 
hand-painted slides had to be depended upon, 
for they were the sole pictures that could be obtained. 
In those days it was common to use a very much 
larger picture for the lantern than at present. Those 
pictures which delighted one or two generations of sight- 
seers at the old Polytechnic, measured about eight inches 
by five. Some of these pictures were most elaborate works 
of art ; so much so, that at the sale of the belongings of 
the Polytechnic in 1881, when the Institution as a place of 
entertainment was broken up, many of these slides real- 
ised as much as fifty shillings each. It is to be feared that 
such hand-painting on glass is now almost a lost art, for 
people will not pay the price which would remunerate a 
competent artist, when they can obtain a more perfect 
representation, as to form at least, by means of a photo- 
graph. The slide-painter of those days used to work both 


in water colour and in oil colour, sometimes, I believe, 
combining the two methods in one picture ; and his first 
proceeding was to draw the outline on the glass, in black 
pigment, with a very fine brush. Those who do not wish 
to dabble in photography, and who have some artistic taste 
may still adopt the same plan, and they will find that with 
a little practice they will be able to draw with a fine brush 
and with a suitable pigment, as finely as they can on paper 
with a pen. The Japanese artists, I may mention, do all 
their work, and even their writing, with a brush, and we 
all know their pictures are not to be despised. It will 
be found that such an outline is easier to produce if the 
glass be first covered with a layer of varnish. Some use 
a weak solution of gelatine in water, to give the glass the 
necessary surface for taking the pigment. A solution of 
sugar has also been recommended for the same purpose. 
A still easier plan of producing diagrams of line drawings 
without the aid of photography is to use sheet gelatine, 
which is sold for the purpose. This gelatine is placed over 
the engraving or other design which it is wished to copy ; 
and the lines are traced with a sharp point, such as an 
etching-needle. Fine black lead is then rubbed over the 
surface with the top of the .finger, with the result that the 
black powder lodges in the scratches, but does not adhere 
to the smooth surface. This plan I look upon merely as a 
makeshift; but I mention it for what it is worth. 

A method by which far better results can be obtained 
was published some years ago by the Rev. Dr. Dallinger, 
the eminent microscopist, who has for a long time used 
slides produced in the way he describes. His plan is 


briefly this. He works with a hard pencil on a piece of 
very finely-ground glass ; afterwards filling in the outlines 
thus made with water colours, and applying a coat of var- 
nish so as to give the necessary transparency to the picture. 
This method he brought before the Royal Microscopical 
Society, and the following extract from his paper describes 
the matter so clearly that all will be able to follow his 
directions : 

" Most working microscopists have felt the necessity, in 
reading papers on their work, of accurate illustration. 
These enlarged drawings fail in matter of detail, unless 
extravagant labour is expended, and considerable skill 
employed. Even then the light of an ordinary lecture 
hall is not enough to enable the most distant of the 
audience to see them. It is only by means of the limelight 
and transparencies that really useful illustrations can be 
given. But here the difficulty is to prepare them accu- 
rately and inexpensively. Photography cannot be employed 
in all cases ; and even where it can be, it involves more 
labour than most microscopists can afford. Drawing and 
painting on glass in the usual method is an art that it takes 
years to learn ; and to employ one who has learned it to 
draw from nature a highly-magnified object, would be to 
introduce unnumbered errors of interpretation, unless our 
artist be a microscopist himself. 

" I obviate all these difficulties by the following method : 
On finely-ground glass, drawing with a black lead pencil 
is as easy as drawing on London board. I get four inch 
squares of glass to suit my lantern, carefully ground on 
one side like the focussing glass of a camera. Now with 



the ground side up, the camera lucida may be used with 
this as well as with drawing-board, if a piece of white 
paper be placed beneath it, and the object drawn in the 
usual way. For outlining and delicate shading I employ 
H H H H and H H H pencils ; for deep shadows I use 
H B. By a very delicate employment of the pencil, 
shadows softer than can be secured by lithography may be 
made. The camera lucida, of course, is not necessary ; we 
may draw with the eye and hand alone. If it be necessary 
to put on colour it may be done cleanly and carefully over 
the shading ; thus one layer of colour suffices. Now of 
course, although we have a perfect drawing of the object, 
with all the detail accurately given, it is not a transparency. 
But we can easily make it one. Thin some good pale Canada 
balsam with benzine to about the consistence of cream ; 
and simply float it over the ground surface of your glass, 
pour off till the drop comes very sluggishly. Then reverse 
the glass so that the corner from which the balsam was 
flowing off be placed upward. Let the return flow reach 
about the middle, then reverse it again, and move it in 
several directions to get the balsam level. This may be 
done with very little practice so that the surface shall be 
undistinguishable from glass. We have now a perfect 
transparency. All that is required is twenty -four hours 
for hardening (keeping the glass level) and then another 
square of glass fastened on to it by strips of paper at the 
edges, with small pieces of card at the corners to prevent 
contact, and it makes an admirable lantern transparency. 

"For obtaining very fine points to my very hard leads, after 
cutting them very long and even ? and grinding them on 


glass paper, I finish them on a square of the finest ground 
glass, and with this beside one in making a delicate 
drawing, a -good, fine working point may be Ue*p*t' 8 loag 
while." ' t, 

There is sometimes a difficulty in procuring ground-glass' 
fine enough for this purpose, and I therefore advise those 
who feel inclined to try this method of producing lantern- 
slides to prepare the glass themselves ; which is somewhat 
tedious, but by no means difficult. Or should they prefer 
it, they can purchase the glass at certain photographic 
warehouses, where it is sold for focussing purposes in the 
camera ; but it is rather expensive. The following direc- 
tions will enable any one to grind the glass for himself : 

First of all, obtain a piece of glass which is both flat and 
perfectly free from bubbles and other flaws. Be careful, 
too, to cut it to the correct size at this stage of the proceed- 
ings, so as to avoid all risk of mistake in this direction 
after it has been ground. The glass is now fixed on a 
table or board by means of four pieces of wood, nailed on 
the board or table so as to clip its four sides. These 
wooden pieces must not be thicker than the glass itself. 
Now procure a piece of plate-glass measuring about three 
inches square, to act as a grinder. Failing this, a piece of 
ordinary sheet-glass can be employed ; but, as it will not be 
thick enough to afford a proper hold for the fingers, it 
should have attached to it a pneumatic india-rubber plate- 
holder to serve as a handle. 

Now take some flour emery and mix it into a thin cream 
with water. Put some of this on the glass, which you have 
fixed to the table, and place the grinder above it ; rub the 


latter over the former with a steady circular motion, taking 
care to coyer every part in turn. This rubbing should 
be <co*itjjnud for about ten minutes, adding water if the 
two, surfaces aeem inclined to stick together too much, and 
occasionally -collecting with a knife-blade the mud which 
oozes out between them, and putting it once more in the 
centre of the under glass. At the end of the time 
named* the glass can be lifted from the table, held under 
the tap for a few seconds so as to clean it, and care- 
fully examined by transmitted light. It will most probably 
show a fine grain, except in certain parts, which remain 
clear as before. These clear portions are depressions in 
the surface of the glass, which the emery has failed to 
reach. The grinding operation must be repeated as before 
until on examination these clear places have disappeared. 

It has occurred to me that Dr. Dallinger's system of 
producing lantern-slides might be modified with advantage 
in the following manner. Coat the glass with varnish 
which dries with a mat surface, and practically gives the 
same effect as ground-glass itself. There are several 
recipes for such varnish, which is used by photographers for 
retouching purposes. Here is one which will be found 


Ground- Glass Varnish. 

Sandarac ... ... ... 90 grains. 

Mastic 20 

Ether - ... 2 oz. 

Benzole Jtoljoz. 

The proportion of benzole added determines the nature of 
the mat obtained. 


The varnish is simply flowed over the glass and allowed 
to dry cold, which it will do in a very few minutes. 
After it is thoroughly hardened it can be drawn upon 
with a pencil in the way described, and can then be 
coloured with water colours tempered with ox-gall, as 
pointed out. We can now make the picture transparent by 
the addition of another varnish, which must be of such a 
composition that it will not dissolve or in any way act upon 
the surface already laid upon the glass. Such a varnish 
would be represented by one not containing benzine as a 
solvent for its gums. I have not tried this method myself, 
and so cannot speak from experience ; but I do not see any 
reason why it should not succeed. 



slides made by the wet process are 
certainly easier to produce than those made by 
any dry method. It is a matter of opinion 
whether these are better in quality than their rivals on 
gelatine, &c., and I know that many believe that a far 
better effect is producible upon a wet plate than upon a 
dry plate. I myself am of the contrary opinion ; but still, 
as there may be many who may be inclined to try the old 
collodion method, my work would be incomplete if I did 
not give directions by which such slides can be produced. 

If the negatives are of the same size as the lantern 
plate ; that is to say, if they consist of quarter plate nega- 
tives, they must be reproduced by contact ; and actual 
contact with a wet collodion film is of coarse out of the 

There is a method by which this difficulty can be ob- 
viated. Attach to the negative a couple of strips of note 
paper, 3 ~ inches apart ; the collodion film can then rest 
against these paper supports by two of its edges during 


the necessary exposure ; but in this case care must be 
taken that the plate is thoroughly well drained, for a drop 
of the silver bath solution, if allowed to get into actual 
contact with the negative, will inevitably spoil it. 

But those who advocate the wet process for lantern- 
slide work nearly always work from larger negatives 
with the camera, and by following the directions now 
given it will be found that very good results can be 

Place the negative to be copied in a suitable frame 
against the window. This can be done by fixing an ordi- 
nary printing frame (with the spring removed) against 
the glass, and by covering up the rest of the window- 
panes with brown paper, or some other opaque material. 
Then support the camera on a stand or table, exactly op- 
posite the negative, taking care that it is square with the 
negative and carefully focus the image on the ground glass. 
A focussing glass is a very great help in this work, for the 
image is often so dimly illuminated that it is difficult to 
ascertain whether it is sufficiently sharp or not. With 
regard to exposure, it is very difficult, in fact impossible, to 
lay down any hard-and-fast line. I can only say that 
with a negative of normal density and with a favourable 
light, the exposure should be about one minute ; but it is 
of course governed by the type of lens used, and the par- 
ticular stop employed with that lens. With a portable 
symmetrical of 5 -inch focus and using No. 4 stop, the 
exposure with a normal negative will be about that which 
I have indicated. 

But the great thing which ensures success in this process 


is to use a proper developer and a bath which is in the 
right condition. This bath should be an old one ; that is 
to say, not a newly mixed one, one, in fact, which would 
give very hard results for ordinary portraiture. 

It should have a small quantity of nitrate of baryta 
mixed in it, say 3 grains to the ounce of bath. 

Develop with sulphate of iron sat. sol. ... 4 oz. 
Methylated spirit 4 oz. 

Add these to a Winchester quart of distilled or rain 
water ; and allow it to stand in the light for some hours, 
next filter it into a clean bottle, and add 4 drops of 

Just before using this developer add to it one drop of 
acetic acid per ounce. This addition ensures a very fine 
deposit, without it the deposit may be granular. The 
exposure should be so regulated that no subsequent intensi- 
fication is required, but if an error of judgment should be 
made the image can be strengthened by adding a drop of 
the silver bath to a little of the developer and flowing 
it over the plate. The glass used should be the 
best, and quite free from flaws of any kind. " Flatted 
Crown " answers this description. It should be care- 
fully cleaned and albumenised. The albumen should 
be flowed over one side of the glass only, and it should 
consist of the white of one egg to a pint of water, with 
the addition of one drop of carbolic acid. 

A quantity of broken glass should be placed in this 
bottle and the whole shaken up into froth, left to settle and 
then filtered through cotton wool. As the plates are coated 
with this albumen mixture, they should be reared up to 


drain, and dry spontaneously on a slip of blotting paper. 
The best collodion to use is " Mawson's Negative Col- 
lodion." The plates should be fixed in hypo of the usual 
strength, and should the image appear to be " dirty " it 
can be rendered clear by being washed over with a solution 
of iodine and iodide of potassium. 

After fixation and after the plates have been thoroughly 
washed, they may be toned in a solution of chloride of 
platinum, one grain to 4 ounces of water, and they 
should remain in this solution until the deposit is darkened 

Beginners very often fail in getting a good tone from 
platinum, and complain that instead of darkening the 
image the salt has the opposite effect. They are recom- 
mended in some formulae to add nitric acid to the toning 
bath, but this is useless unless the platinum salt be 
neutralised in the first instance. The proper mode of 
procedure is to break the tube containing the platinum 
crystals (this chemical, like chloride of gold, is on account 
of its deliquescent property always sold in an hermetically 
sealed glass tube) into a certain quantity of distilled water. 
A convenient plan is to break a tube containing 1 5 grains 
into 15 drachms of distilled water : one drachm of the 
liquid will then represent one grain of platinum chloride. 
Test this liquid before use with litmus paper: if it show by 
the paper turning red that it is acid, we may be quite sure 
that it contains free hydrochloric acid, which will have a 
bleaching effect upon the photographic image. The liquid 
must therefore be neutralised by the addition of a few 
grains of carbonate of soda, after which it must be 


rendered sufficiently acid with nitric acid to slightly redden 
litmus paper. If the operator is careful to follow these 
directions he will have no difficulty in toning his trans- 
parencies with platinum. 

We may summarise the order of operations as follows : 

Albumenise the glass. 


Coat with collodion. 

Sensitise in silver bath. 



Fix in hypo. 


Clean with iodide solution if necessary. 

Tone with platinum. 



The operations conclude with giving the film a coat of 
transparent varnish. Any good varnish may be used, but 
care must be taken if the slides are to be subsequently 
coloured, that some varnish upon which turpentine has no 
action be employed; otherwise the turpentine used in 
colouring will most surely mingle with the varnish and 
ruin the picture. 

It is hardly necessary to add that the operations of sen- 
sitising, developing, and fixing the plate must be conducted 
in a non-actinic (red) light, and that all precautions usually 
taken in dealing with photographic chemicals must be 
observed. The directions are written for those who have 
already mastered the details of such work. 



HERE are many dry collodion methods which, 
were originally designed for ordinary nega- 
tive work in the camera, but which have 
long ago been superseded by the far quicker and 
more certain gelatine process. Some of these plates, 
however, although they have been discarded for the 
main purpose of photography, are still used by many 
workers for the manufacture of lantern-plates where great 
speed is a matter of secondary importance. 

For many of these processes the silver bath is still 
required, the plate after being sensitised therein, being 
flowed over with some preservative solution, the function 
of which is to keep the pores of the collodion film in such 
a condition that it will not dry into a horny state, im- 
permeable to any developer which may later on be 
applied to it. As full particulars of these processes can 
be found in most photographic text-books, I shall content 
myself with giving here only a brief survey of them, 
reserving details of working for the more modern methods 
of producing lantern-slides on gelatine plates. 


Many of these old processes differ only in the kind of 
preservative fluid applied to them, and from the nature 
of this preservative they usually are named. Thus we 
have the Tannin process, the Honey process, the Coffee 
process, &o. Taking the first named, let me cite it as an 
example of the others. 

The glass-plate which is to bear the picture is first of all 
carefully cleaned. It is then edged with india-rubber 
solution, albumen, or some other body which will prevent 
the film from slipping off the glass during subsequent 
operations. Next it is coated with ordinary negative 
collodion, to which two grains per ounce of bromide of 
cadmium may be advantageously added. It should now 
be dipped in a silver bath which has been made distinctly 
acid, by the addition of a few drops of nitric acid. After 
thus sensitising the plate, it must be well washed to remove 
all free silver, after which the preservative is applied, 

Tannin ... ... 35 grains. 

Distilled water ... 4 ounces. 

After the plates are dry they are ready for use, but will 
only remain good for a week or two. 

In another process which gives good results coffee is used 
as the preservative. In this case the bath can be made 
very acid, by the addition of one-fifth of its volume of 
glacial acetic acid. The plate is edged, and sensitised in 
the bath, and is then flowed over with an infusion of 
ground coffee. After drying, these plates will keep for 
some months, and will give fine results. The development 
is brought about by a plain solution of pyrogallic acid, 


say two grains to the ounce of water, and is afterwards 
strengthened by citric acid and silver. 

A far greater importance is attached to the next method 
under disscussion, by which the very finest results can be 
obtained ; but it requires, at every stage of the process, 
such great care that few in these days care to take it up. 
Still it has a commercial importance, and is known as the 
Albumen process. Here is a sketch of the operations in- 
volved in it. 

After the plate of glass has been rendered chemically 
clean it is coated with a film of albumen from fresh eggs, 
to which has been added some iodide and bromide of 
potassium. The plate is then inverted on its pneumatic 
holder, and revolved by means of a vertical cord attached 
to the bottom of that holder, so that by centrifugal force 
some of the albumenous coating is scattered, leaving the 
thinnest possible film on the glass. The plate is then 
dried, as yet insensitive to light. Next it is immersed 
in an acid silver bath for about three minutes, and after 
washing with several changes of water, a preservative 
consisting of a saturated solution of gallic acid, is applied 
to it. Drying by gentle heat completes the manufacture 
of this form of plate. The development is brought about 
by a saturated solution of gallic acid, to which has been 
added a few drops of silver nitrate. 


We will now give our attention to the beautiful 
Collodio-bromide process, a brief description of which is 
only necessary, for the collodion emulsion for the im- 


mediate coating of the plates can be bought ready made, 
with full instructions for coating and development. 

This method yields results which cannot easily be beaten, 
It was introduced about twenty years ago by Messrs. 
Bolton & Sayce, and a number of good workers have 
since taken it up successfully. As its name implies, a 
collodion is employed containing bromide of silver, and 
although many might be deterred from attempting it, from 
the fancied difficulties which it presents ; yet, in practice 
it is by no means a complicated process to work. It has 
certainly a great many advantages. When the sensitised 
collodion is once compounded it will keep for a long time. 
Plates can be coated with it a dozen at a time if required 
and after being dried by artificial heat are ready for 
immediate use. When the printing from the negative has 
been performed, these plates, after development and a 
minute's washing, can be dried, and the slides are finished 
and ready for the lantern. 

A plain collodion is first of all made with high tempera- 
ture Pyroxyline, and the usual solvents, ether and alcohol. 
To this is added ammonium-bromide and citric acid. The 
silver is now dissolved in as little water as possible, and is 
added to the bromised collodion. The emulsion is then set 
aside to ripen for some hours, is poured out into a dish for 
the solvents to evaporate, and is then broken up into small 
pieces and washed in several changes of water, so as to get 
rid of the soluble salts which are not required. All these 
operations are, of course, conducted in non-actinic light. 
When these pieces have been finally drained as closely as 
possible, they are once more dissolved in the requisite pro- 


portions of ether and alcohol, and, after filtering, the re- 
constructed emulsion is ready for coating the plates. They 
can be developed by a weak alkaline developer with pyro, 
or by the ferrous-oxalate method, which will be described 
later on, Mr. W. Brooks, of Reigate, has made a study 
of this process, and supplies the emulsion ready made. 
Messrs, Mawson and Swan have also lately advertised it, 
so that it is hardly worth while for the worker to make it 
for himself, 


This method yields results which cannot be sur- 
passed, but it may be looked upon more as a com- 
mercial process than one suited to the amateur worker, 
for it necessitates the use of expensive plant. I shall 
therefore dismiss it with a somewhat brief description, 
albeit my chapters on slide-making would hardly be com- 
plete without it, In the first place a relief is obtained by 
employing gelatine, containing one of the bichromates of 
the alkalies bichromate of potash, for instance. This 
relief is placed upon a sheet of lead, and after the two 
have been fixed in a steel frame, they are submitted to 
hydraulic pressure, with the curious result that the tender 
gelatine film preserves its delicate outlines, but the leaden 
plate gives way, and these markings are pressed into it. 
This leaden plate then forms a mould of the future picture, 
its deepest parts representing the shades of that picture, 
and its higher parts the lights. This is placed in a special 
press, and a pool of gelatinous ink (made by dissolving any 
suitable pigment in a warm solution of gelatine and water) 



is poured upon the mould. The square of glass which is 
to bear the picture is placed on this pool of ink, and the 
pi-ess is lightly brought down upon all. The slide is left 
thus until the gelatine has had time to set, when the 
glass is lifted from the mould, and the picture in all its 
delicate details is left upon it. This beautiful process, 
which may be looked upon as the most perfect of all the 
mechanical photographic processes, was due to the genius 
of the late Mr. Woodbury, who, shortly before his lamented 
death, modified it so that it might be practised by ama- 

This modification is known as the Stannotype pro- 
cess, tinfoil being employed as a substitute for the work of 
the hydraulic press. The gelatine relief is attached to a 
plate of glass by a suitable cement. Its surface is then 
coated with india-rubber cement, and a sheet of ordinary 
tinfoil is placed above it. The whole arrangement is now 
passed between a couple of india-rubber rollers, such as 
are attached to a domestic wringing-machine, so that the 
tinfoil is forced into the interstices of the picture, We 
thus obtain a metallic-faced mould without the interven- 
tion of the hydraulic press, and this mould is afterwards 
treated with warm gelatinous ink, and prints taken off, as 
in the Woodburytype process. In the latter process, how- 
ever, a negative is employed to give the necessary relief, 
and in the Stannotype a positive. Both of these methods 
give the best results for pictures where there is not a large 
expanse of sky, or other high light ; for in such a case 
a slight deposit of the pigmented gelatine is likely to spoil 


the transparency of such lights, and in a good lantern slide 
they should be represented by clear glass. 


For some inscrutable reason, it used to be the common 
opinion among those who ought to know something about 
the matter, that the gelatine process is unsuitable for lan- 
tern transparencies. The introduction lately of gelatine 
lantern plates into the market has done much to correct 
this error ; but still there are numerous persons who hold 
to the belief that the ordinary gelatine plate, such as is 
used for negative work, will not produce a good trans- 
parency. For years I have proved the contrary, and with 
regard to the quality of the transparencies produced, I have 
seen few to equal them. 

The first operator who turned out successful work of this 
character was Mr. Kennett, who has the greater honour 
of being the first to make gelatine plates a marketable 
commodity. His method of working was to employ a slow 
plate, to expose it under a negative in a printing frame for 
the fraction of a second in daylight, or for a longer time 
by lamplight, and to develop by either the alkaline or 
ferrous oxalate method. The plate was afterwards flooded 
with pyro and silver and toned with gold. 

The introduction of chloride plates, which give beautiful 
effects, may deter some from trying what can be done by 
ordinary gelatino-bromide plates. But for the amateur 
whose time is otherwise occupied during daylight, the latter 
process has many advantages. The chief one is that, while 

i 2 


the exposure of a chloride plate to lamplight will occupy 
about three minutes, a bromide plate can be successfully 
exposed in less than three seconds, so that a number can 
be exposed in an hour or two. 

I have already pointed out how a reduced positive can 
be readily obtained from a negative by means of the 
camera. I will now suppose that the negative from which 
the transparency is to be taken, is on a plate, and, there- 
fore, the right size for the lantern slide, and that the pic- 
ture is to be printed by contact in a printing frame. 
The requirements are a red lamp, a gas or paraffin 
lamp, which can be readily turned up and down, and a 

As in most photographic operations, correct exposure is 
the main consideration, but whereas where daylight is 
concerned, this exposure is always difficult to hit upon, 
because the light varies so much under different circum- 
stances ', here, where we have a lamp to work by, we can 
measure its duration to a nicety. 

I may mention here that there is a form of gas-burners 
sold which is very useful in this work. It is fitted with a 
bypass, so that it is never actually turned out. A blue 
bead of light remains, which is quite shielded from view, 
and this permanent flame ignites the full amount of gas 
when the stop-cock is turned on. The operation of print- 
ing a transparency consists in placing the negative in the 
frame, and placing upon it, film to film, a gelatine plate, 
measuring 3 x 3 inches. The frame is closed, and is 
held within a short distance of the lamp, which is turned 



up for a brief period, and then turned down to darkness 
once more. But how must this period be measured ? In 
order to answer this question I must call attention to a 
certain optical law which I have attempted to put in the 
form of diagrams : 

FIG. 38. 

Fig. 38 illustrates the manner in which the light rays 
from a candle strike out all round it like the spokes of a 
wheel ; but, for simplicity sake, the rays in one direction 
only are shown. Let A represent our printing frame held 
at 1 foot from the light source, and let us suppose that 
at that distance the plate contained in it will require one 
second's exposure. Now let us expose a similar plate at B, 
which is 2 feet from the light source, what exposure will 
it require? "Two seconds," the tyro will probably 
answer ; but he would be wrong, the plate at double the 
distance will require four times the original exposure ; at 
treble the distance, nine times the original exposure. In 



other words, " the intensity of illumination on a given sur- 
face is inversely as the square of its distance from the source 
of light" 

FIG. 39. 

Fig. 39 will perhaps make the matter still more plain. At 
1 foot from the candle the square marked i receives a 
certain amount of light ; at u, that light is spread over a 
surface four times the area of the first ; and at in over a 
surface nine times as large as I. This law, which is really 
of a very simple character, the operator should have con- 
stantly in his mind, as he exposes his plates, to artificial 
light under a negative. 

The method of development which I recommend is by 
means of ferrous oxalate, and it will be found that the 
transparencies produced by- it require no toning whatever. 
I make my own potassic oxalate, and find it, moreover, 
reliable ; the operation is simplicity itself. In a large 
basin dissolve half a pound of carbonate of potash (salts of 
tartar) in a pint and a half of warm water. Now add 
gradually oxalic acid, a few cr3 T stals at a time, for the 
effervescence is very violent, and difficult to control if 
much be put in at once. When six ounces of the crystals 


have been so added, set the basin aside for an hour or two, 
then stir its contents with a glass rod, and test with blue 
litmus paper, adding crystals of acid until the paper turns 
slightly red. Add to the liquid 30 grains of potassic 
bromide, allow to settle, and bottle off for use when clear. 

But those who wish to avoid the trouble of making 
their own potassic oxalate can buy the crystals at any 
photographic dealer's, in which case its solution should be 
made with boiling water, and well stirred until all crystals 
have disappeared. One pound of oxalate will require 
just a quart of water to make a saturated solution. If 
more water be used, the solution will not be a saturated 
one, and will, when mixed with the iron, throw down a 
muddy red precipitate, and be useless for developing pur- 
poses. The iron must be added to the potash, and not vice 
versa, or the same effect will be produced. I have found 
that with this developer it is always advisable to soak the 
exposed plate in water as a preliminary step. The gelatine 
surface then takes more kindly to the solution, and greater 
density is attained. 

The development should be carried on until the picture 
looks overdone, for it must be remembered that it has to 
be ultimately exhibited by transmitted light, and we view 
it in the developing dish by reflected light only, but hold- 
ing it up to the red light and looking through it we can 
judge well when the developing action ought to be stopped. 
Now follows a rapid rinse under the tap, a few minutes' 
immersion in alum and water, and fixing in fresh hypo. 
If ordinary household water has been used, the film will 
show a milky veil. This is quickly removed by a ten per 


cent, solution of sodic citrate, poured on and off, and gently 
rubbed upon the gelatine surface with a plug of cotton 
wool. This treatment is not necessary if rainwater is 
available. Messrs. Mawson and Swan supply an admirable 
plate for lantern-slide work. It can be used for reducing 
in the camera, or for contact printing, and is amenable to 
more than one method of development. 

At one of the exhibitions this firm showed a specimen 
frame of four transparencies from one negative, each 
developed by a different formula, and showing a difference 
of tint for each. I was so pleased with their appearance 
that I asked for particulars, and the firm kindly supplied 
me with the four formulae in question. Here they are : 

A. Meta Bisulphite Developer. 
B. Carbonate Soda 
C. Ammon. Sulphite 
D. Ferrous Oxalate 



Pyrogallic Acid ... ... ... ... 40 grs. 

Meta-bisnlphite Potass 120 

Bromide Ammonium ... ... ... ... 40 ,, 

Distilled Water 20 ozs. 

Liquor Ammonia ... .. t ... ... 2 drms. 

Distilled Water 20 ozs. 

Mix equal parts of A and B just before using. 


Sodic Sulphite 
Brom. Potass... 
Hydrochloric Acid 
Distilled Water up 

... 40 grs. 
... 20 
... 40 mins. 
to 20 ozs. 

Garb. Soda 
Sodic Sulphite 
Distilled Water . . 

. 1 oz. avd. 
. 20 fluid. 

Equal parts. 



Between development and fixation immerse plate in Sol. of Alum, 
1 oz. in 20 ozs. water, washing carefully before and after. 


Bro. Ammon. ... 
Sulphite ... 
Distilled Water to 


Mist. Ox. Potass 
Brom. Potass 
Distilled Water 


... 40grs. 
... 60 
... 20 ozs. 


Liq. Ammonia, 880 ... 
Distilled Water ...20 

Equal parts. 


... 20 oz. avd. 
... 40grs. 
.. SOozs.fld 


Ferrous Sulphate 
Distilled Water 
Sulphuric Acid 

6 oz. avd. 
18 fluid 
12 mins. 

Add 7 parts of I. to 1 part of II. just before using. 


There are certain main principles to be observed in 
copying a photograph, or anj other kind of picture, if a 
satisfactory negative, fit for printing a lantern slide from, 
is to be expected. The copy should be illuminated by 
diffused light only, and should never receive the direct 
rays of the sun. A cloudless day is the best to choose, 
for then the light is regular, and when the exposure has 
been correctly calculated for the first picture, it will, during 
some hours of the day, be right for the rest. At least this 
is true, if we are copying a series of pictures of the same 
dimensions. But, if our first copy is, say, 12 inches across 
and our next one only carte de visite size and we want to 
reproduce a negative of each, measuring 3J x 3J (the 
standard size for lantern pictures), our camera must in the 


latter cases be so much extended that the exposure must 
be proportionately increased. 

A picture under glass will seldom give a good result, 
for the surface will take up reflections from surround- 
ing objects, which may not perhaps be noticed on the 
focussing screen, but which will most surely become dis- 
agreeably evident in the negative. A highly glazed 
albumenized print is objectionable for the same reason, 
but can be generally coaxed into a position in which no 
mischief of the kind is apparent. Steel engravings have no 
gloss, but they seldom make good pictures for the lantern 
screen, their details being too fine. A first-class wood 
engraving is far better for the purpose, and as its value is, 
as a rule, not very great, it can be judiciously touched up 
before being photographed. Perhaps the artist of such a 
picture would be horrified at his work being thus interfered 
with, but the touching up indicated is quite legitimate. 
Let me further explain my meaning. Suppose that in one 
of our illustrated periodicals there is a representation of 
some current event which we want for our lantern. If it 
is an interior view, it will probably require no doctoring. But 
if a landscape, or a group of figures with a sky back- 
ground, then certain parts should be suppressed. The sky 
is not white, but consists of a number of parallel lines with 
clouds interspersed ; effective enough in the print, but not 
suitable for reproduction in an enlarged form. These lines, 
which seem to mingle so well, giving the effect of a general 
soft " tint," will on the lantern sheet look like what they 
really are a series of detached bars right across the picture. 
To get rid of these lines, the outline of the figures, and 


other objects which stand against the sky, should have a 
broad margin painted round them in Chinese white, leaving 
the main body of the sky to be blocked out with black 
varnish in the negative itself. 

I have done excellent work with Ross's portable sym- 
metrical lens No. 3 which has a focus of 5 inches. Of 
course, other lenses will do well for copying, but if of 
longer focus, the camera must have an extending front 
fitted to it. Very few cameras pull out long enough to 
photograph a very near object, unless a short focus lens is 
employed. As a guide to exposure, I may mention that 
in copying wood-cuts and photographs with the above- 
named lens, and using a fairly-rapid gelatine plate, it 
averages 17 seconds with stop No. 4. It is as well to focus 
with full aperture of the lens, and to insert the stop just 
before exposure. One more hint. It is sometimes very 
difficult to sharply focus a soft photograph which has no 
sharp lines in itself. The difficulty is obviated by affixing 
to the middle of the copy any little piece of printed matter, 
wetting it with the tongue for that purpose. Only be 
careful to remove it before exposure, or your negative will 
faithfully record the little dodge. 

It would seem a very simple matter, to one who has not 
tried it, to fasten a picture upon a wall in a good light, 
stand the camera on its tripod in front of that picture, and 
proceed to copy it. But difficulties crop up when we want 
to reduce that picture to a certain size, and to keep the 
camera square with the copy, so as to prevent distortion. 
With head beneath the focussing cloth, the struggle to 
adjust the tripod legs is quite distressing. I myself found 



so much difficulty in getting the camera into the exact 
position required, that I constructed a special piece of 
apparatus for the sole purpose of copying. To this acces- 
sory, which works most perfectly, I now direct atten- 
tion. It is simple in construction, and anybody who knows 
how to handle a few tools can put it together with ease. 
The amateur may prefer to employ a professional carpenter, 
but there is always a difficulty in getting the British work- 
man to make anything that is at all strange to him. My 
advice is, therefore, if you want the thing done well, do it 
yourself (see fig. 40). 

FIG. 40. 


A is a base board, fixed on legs, as shown. It will be 
evident that a spare table, or even the top of a packing- 
case, would do as well, but it must be firm. Upon this base, 
and fixed firmly to it, is a kind of railway formed by two 
parallel grooves. D is a skeleton carriage furnished with 
two runners at the bottom which will fit the grooves in 
A, so as to run easily to and fro. The carriage D is also 
furnished with grooves, and these are for the reception of 
the runners affixed to the super-carriage, E. Upon E is 
fastened the photographic camera, the camera screw being 
placed through the centre hole for that purpose. 

In use, the picture to be copied is pinned to the back- 
board, F, and I may mention as a detail of some im- 
portance, that the little bead-headed arrangements known 
to drapers as " ladies' bonnet-pins " are best for the purpose. 
The camera is placed on E, E on D, and D placed on the 
rails of the baseboard, A. We thus have two separate 
movements at our disposal in getting the image of the copy 
focussed centrally on the ground glass. A furnishes the 
to and fro movement, and the grooves on D give the right 
and left movement. The board, F, runs between upright 
grooves, and thus we have a vertical movement. With 
this simple contrivance a picture can be focussed in a few 
seconds, and the camera all the time is bound to keep square 
with the copy. A 3 -inch circle drawn in pencil on the 
ground-glass of the camera is useful as a reminder of the 
size to which the picture must be reduced. 

Lastly, this useful contrivance can serve another pur- 
pose. We may wish to obtain a reduced positive on glass 
from a larger negative. We can do this direct in the 


camera by placing the negative to be copied in an opening 
in the board, F, marked by a dotted line in the illustra- 
tion. A couple of laths can then be placed above, so as to 
rest at one end on the camera, and at the other end on the 
top of the board, F. These laths will serve as a support 

FIG. 41. 

for a dark cloth, which can be thrown over all. A sloping 
piece of white cardboard placed behind F (also indicated 
by a dotted line) will throw reflected light from the sky 
through the negative. I give no dimensions for this copy- 
ing machine, for the maker must be guided by the size 
of his camera, the focus of his lens, and his general 
requirements. A compound frame for negatives of various 
sizes, as shown in fig. 41, makes this copying-machine 



ILL makers of commercial gelatine plates put for- 
ward the quality of rapidity as being the one 
thing needful in modern photography, and ad- 
vertise their wares as being ten, twenty, or even sixty 
times as quick in operation as the old wet collodion 
process. Such rapid plates are not the best for trans- 
parency work, and as no maker will acknowledge that 
his plates are slow, although opinions may be divided 
upon the matter, and as slow plates are the most 
suitable for lantern slides, the operator who aims at the 
best work may wish to try his hand at making them for 
himself. Of the many formulae which I have tried for this 
particular purpose, I prefer that first introduced by Dr. 
Eder, which I have slightly modified. Gelatine plate 
making is by no means easy work, but the method which 
I am about to describe presents fewer difficulties than 
most others. 

The apparatus required need only be of a very homely 


nature, and such as can be found in most households. 
Here is the list : An earthenware pot with a cover to it, 
of about one pint capacity ; a glass tumbler ; a preserving- 
pan or saucepan standing on a tripod, with a spirit-lamp 
or Bunsen flame beneath it; a thermometer, two glass 
stirring rods, a square of Berlin-work canvas, an earthen- 
ware colander, and a dish. In the earthenware pot put 
the following : 

Gelatine ... ... ... ... 110 grains. 

Potassic Bromide... ... ... 62 ,, 

(Ten per cent.) Solution of Salicylic Acid in Alcohol, \ ounce. 
Water ... ... ... ... 2 ounces. 

I recommend the use of either Autotype, the Swiss, or 
Henderson's make of gelatine. After being weighed it 
should be cut up into strips with scissors and placed in the 
jar with the other ingredients. With a glass rod press 
down the gelatine into the water, so that every particle of 
it is wet and softened. Set aside for ten minutes to swell. 
Now half fill the preserving-pan with warm water, and 
place the flame beneath it. The thermometer should be 
placed in the pan, so as to check the temperature, which 
should not be allowed to rise about 96 Fahr. Place the 
pot containing the gelatine in the water, taking the precau- 
tion to put a piece of thick paper beneath it, so that it 
does not actually touch the heated bottom. 

The gelatine will very gradually melt, and the opera- 
tion may be hastened by an occasional stir with the glass 
rod. Even when it becomes quite limpid, little particles 
of undissolved gelatine may be floating about in it 
and these should disappear before proceeding further, or 


they will form insoluble particles, which will lead to 
difficulties later on. In the glass tumbler place 

Silver nitrate ... 77 grains. 
Water ... ... 2 ounces. 

The common tap water employed will, on account of the 
salts which it contains, turn milky in appearance when the 
silver is added. This is of no consequence. The crystal* 
can be crushed under the water by another glass rod, 
and complete solution will soon be effected. (The tyro 
must be most careful to keep each stirring rod distinct, or 
he will spoil the entire work.) When the crystals have 
all disappeared, pour into the silver solution, drop by drop, 
some strong liquid ammonia, stirring the solution vigorously 
all the time. The liquid will turn coffee-coloured, owing 
to a precipitation of silver oxide, but as more of the 
ammonia is added this precipitate is redissolved, and the 
solution becomes as clear as ordinary water. Only just 
sufficient ammonia should be added to accomplish this 
result. Now place the glass tumbler in the pan beside 
the vessel containing the gelatine mixture, and leave it 
there to warm for about fifteen minutes. All the fore- 
going operations can be conducted in the full light of day, 
but now, when the two solutions have to be blended to form 
a sensitive emulsion of bromide of silver, the light of the 
red room only must be called into requisition. 

The flame beneath the pan, or water bath, is now no 
longer required, so let it be removed. Take both the gela- 
tine and silver vessels from the pan, and place them on the 
table. Now stir the gelatine briskly, and add a small 



portion of the silver solution at a time, until all of it is 
transferred to the earthenware pot. Wash out the silver 
glass with half an ounce of water and add that too. The 
newly-formed emulsion should now look like cream. Place 
the cover on the jar, and put it back once more in the 
warm water (without any flame beneath it) for fifteen 
minutes. At the end of that time pour it out into a dish 
or plate to set, and cover it over so that neither light nor 
dust can trouble it. This will complete the first stage of 

In a few hours, according to the general temperature, 
the emulsion will have set into a firm jelly. It must 
now be washed to get rid of certain extraneous matter 
which has been formed and which is not wanted. The 
silver nitrate has combined with the bromide of potassium 
to- form silver bromide, the required salt, which is sensi- 
tive to light, but at the same time nitrate of potassium 
(saltpetre) has also been formed, and must be eliminated. 
As this latter is soluble in water, while the silver bromide 
is insoluble, the matter is not a difficult one to accomplish. 
By dividing the jelly into shreds, and putting it into 
several changes of water, this universal solvent gets to 
every side of it, so to speak, and the saltpetre is quickly 
got rid of. Scrape up the jelly with a silver spoon, or a 
slip of glass, and place it in the middle of the square of 
canvas, which has been previously wrung out in water. 
Gather up the ends so that the jelly forms a ball confined 
within the canvas. Now place in a large pan of water, 
and squeeze and twist the canvas with the hands (under 
water) so that the jelly is forced through the meshes of the 


fabric like so much vermicelli. It will presently sink to 
the bottom of the pan. Now pour off the water above it, 
and fill up with fresh. Let the pan rest for five minutes, 
and repeat the operation half a dozen times. The emulsion 
must now be strained. 

A square of cambric, the size of a handkerchief, is 
squeezed in water, and put in the colander, so as to form a 
lining to it, with the corners hanging outside. Pour the 
divided emulsion into this, when most of the water will 
at once run off, and still more may be made to do so by 
gathering up the corners of the cambric in the hands and 
gently squeezing the pudding-like mass. Once more open 
the cloth, and pour into the contained emulsion an ounce 
of methylated spirit. Again squeeze up the cloth, after 
which the gelatine shreds can be spooned up, placed in a 
clean jar, and tied over with a light-tight cover. So ends 
stage number two. 

There are many who say, with much truth, that the real 
difficulty of plate-making begins after the foregoing opera- 
tion of making the emulsion, for a great many fail in the 
mechanical work of coating the plates, which is the next 
and final operation. Before this is attempted the decks 
should be cleared for action. The operator must have on 
his table a carefully levelled piece of slate or plate glass, 
large enough to contain at least one dozen plates, laid 
edge to edge. He will also want a jug with a good lip 
from which to pour the emulsion, a glass rod to guide 
it over the plate which he is coating, and a pneumatic 
holder. The jar of emulsion must first of all be placed in 
the water bath at the old temperature of 96 for an hour 
K 2 


or two, during which time it can be conveniently stirred 
once or twice (by red light only, of course). If the cover 
of the jar be really light tight, this melting operation can 
go on in daylight, and at the same time the glass to be 
coated can be cleaned. Polish each glass with a little 
whiting and water, and when dry rub the side to be 
coated with a leather damped with spirits of wine. This 
will counteract any repellant action when the emulsion is 
applied to the glass surface. When all the glasses have 
been so treated, wrap them in packets of two dozen each, 
in clean paper, prepared side upwards, and put them on 
the kitchen hob to warm through. (This latter precaution 
is only necessary in cold weather.) The emulsion must 
now be filtered. 

The best form of filter is a lamp chimney with a flange 
on its lower orifice, over which a piece of damp wash- 
leather (which has been washed in soda and rinsed in 
many changes of water) can be tied. When all is ready 
for commencing to coat, this filter is held over the mouth 
of the jug (both should be rinsed out with warm water 
the instant before), and the emulsion is poured steadily into 
its upper opening. In a minute it will run through the 
leather into the jug below, and will be quicker in its move- 
ment if a pressure of air is kept upon it, by applying the 
lips to the upper end of the glass. Now comes the coating 

Let the operator seat himself at his table so that the 
slate or glass slab is between him and the red light. 
Place the glass rod in the jug of emulsion, and when in 
the act of pouring keep the rod back with the thumb of 
the same hand that is holding the jug. Take the topmost 


glass plate, fix it on the pneumatic holder, hold it level, 
and ponr a small pool of emulsion in its centre. By inclin- 
ing the plate a little, the pool will run to the two further 
corners, and can afterwards be guided across the whole 
plate with the help of the glass rod. The plate is then 
slid on to the slab, where it will speedily set, and the glass 
rod goes back into the jug. Each plate is treated in the 
same way until the slab is full, by which time its first 
occupants will have set, and can be reared up to dry in 
shelves, or a proper drying cupboard. The glass chosen 
should be as thin and as free from bubbles as possible, and 
can be of the standard lantern size, 3 J by 3J inches. But 
as experience is gained the operator will find it more con- 
venient and economical of time to coat plates 6 J by 6 \ inches, 
which can afterwards be cut across twice with the dia- 
mond, to form each four lantern slides. 


My own favourite process for lantern slide making is the 
gelatine-chloride, which has many good points to recom- 
mend it. It is suitable only for contact printing, there- 
fore the negatives used must be small ones only. Capital 
chloride plates can be purchased nowadays ; but for those 
who prefer to make their own, I can confidently recom- 
mend the following formula : Mix up the three solutions 
A, B, and C. 


( Water (distilled) .. 

Silver Nitrate 

Water (distilled) .. 

Ammonium Chloride 

Water (distilled) .., 

300 grains. 

4 ounces. 
240 grains. 

4 ounces. 
100 grains. 

2 ounces. 


Melt by heat, but not above 120 Fahr. Then in a 
yellow light, pour B into A, stirring rapidly all the time, 
and finally adding C. Allow the emulsion thus made to 
remain for one hour, at the temperature already stated, 
and then put aside in a dish to set. The washing, filtering, 
and coating operations are the same as those described for 
bromide plate making. The bright yellow light allowable 
is a great help to comfortable working of this process. 

Chloride plates are useless, on account of their slowness, 
where a slide has to be reduced, by means of the camera, 
from a negative larger than itself. Nor do I advise the 
amateur to adopt them unless he can work by daylight, 
or is fortunately situated like one I know, who lives oppo- 
site to an enterprising tailor who displays an electric arc 
light in front of his door. For the chloride plate is most 
insensitive to yellow light, such as that afforded by gas. 
For this reason, most commercial makers advise that the 
light chosen should be that procured by burning an inch of 
magnesium wire at a distance of so many inches from the 
printing-frame. This advice is not difficult to follow, but 
it is very difficult to make two pieces of wire give out 
exactly the same amount of light ; for magnesium wire has 
a habit of dropping down in a languid manner under the 
influence of its own heat, and going out suddenly when it 
ought to shed its radiance abroad. With diffused daylight 
all is plain sailing. The negative, with its chloride plate 
in contact with it, is exposed, say, for three seconds to 
daylight, and is then dropped into the developer. Here 
is a good one, devised, if I remember rightly, by 
Mr. Edwards : 


C Neutral potassic oxalate ... ... 2 ounces. 

A 3 Sal ammoniac ... ... ... 40 grains. 

( Water (distilled) 1 pint. 

f Iron sulphate ... ... ... 4 drachms. 

p. \ Citric acid ... ... ... ... 2 

B 1 Alum 2 

(. Water (distilled) 1 pint. 

For use, pour a portion of B into an equal quantity of A. 

If the operator is accustomed to the ferrous oxalate 
developer pure and simple, he will find that it will develop 
this description of plate, but it is better for being restrained 
with a few drops of 10 per cent, solution of sodic citrate. 
Whether he use one or the other, let him be particularly 
careful in the matter of cleanliness of fingers. A hypo- 
defiled finger will spoil the developer instantly. To avoid 
this disaster, the potency of which I have learned by 
sad experience, I have adopted the following method of 
working : 

I use a brilliant yellow light, so that I can work comf ort- 
. ably, for chloride plates are, as already stated, insensitive to 
yellow rays ; the developing tray stands in front of it, and at 
one side is placed a large tray filled with water, to which a 
little alum solution has been added. Hypo is, for the pre- 
sent banished from the scene altogether. I expose my plate, 
and put it into the developing solution. In a few seconds 
the picture flashes out in the unceremonious manner com- 
mon to chloride plates. I hold it up to the light, look 
through it, and find that it is but a ghostly image after all. 
I expose another plate in an adjoining room, and put it by 
the one which is in course of development, and which by 
this time has most likely gained sufficient density. If it 
has, I wash it for a few seconds under the tap, and drop it 



into the alum tray ; and so on, until perhaps a couple of 
dozen plates have been treated in the same way. I then 
light my gas-lamp, mix up a tray of fresh hypo, large 
enough to accommodate half a dozen plates at a time, and 
proceed to fix my plates. They fix rapidly, and as fast as 
they are done, back they go into the weak alum solution, 
until, when the batch is finished, I proceed to wash them. 
This I do by placing them in a metal rack (see fig. 42), 
and changing the water occasionally during an hour or so. 

FIG. 42. 


Hitherto I have said nothing with reference to the best 
kind of negative for lantern- slide making ; the worker will 
find out, after a few trials, that some of his negatives will 
yield, without much trouble, a first-class result, whilst others 


seem reluctant to give anything but a very poor trans- 
parency. A really good negative will give a good print 
on paper, glass, or indeed on any other possible material, 
but at the same time a negative, which from its thinness 
would require special management in ordinary printing on 
albumenised paper, will yield a fine transparency on glass 
with half the trouble. In other words, a negative taken 
purposely for lantern work need not be so dense as one 
destined for the ordinary printing-frame. The precautions 
used in dealing with a thin negative in the one case, must 
be observed in the other ; for instance, the careful printer, 
in producing a paper print from such a negative, will take 
his frame far from the window of his room, and give it a 
very protracted exposure, and, by coaxing it in this way, a 
good dense print is obtainable. Exactly the same treat- 
ment is necessary in producing a lantern-slide from the 
same picture. Instead of holding the printing-frame a foot 
or two from the gas-burner, as already recommended, let it 
be removed 6 feet away from the flame, and be given a 
greatly-increased exposure by the rule already indicated. 

I have advised that the focussing-screen of the camera 
should be marked with a 3-inch circle, to which the 
picture should be limited. A still more effective plan, 
however, is to cover the ground-glass with a card- 
board mask, having a 3-inch hole in its centre, which 
can be placed in situ when required. The operator can 
then see at a glance whether his picture is nicely composed, 
and will have a very good idea of its ultimate appearance 
as a lantern-slide on the sheet. Most photographers carry 
into the field with them more than one lens, and it is espe- 


cially necessary that he whose negatives are intended to 
yield lantern-pictures of a uniform size should do so. The 
beginner is, perhaps, not likely to see the advantage of this. 
Let me point it out. Suppose that he has focussed the 
image of some wayside cottage, and finds to his chagrin 
that the building fills up all the proscribed circle, and that 
the surrounding foliage and other accessories which really 
make up the beauty of the scene, as presented to the eye, 
are "far, far away." His natural impulse would be to 
carry his camera farther from the object, but a blank wall 
behind him forbids him to do this. But with a shorter 
focus-lens, which should screw into the flange fitted on his 
camera, the accident can be immediately remedied, and 
he can proceed on his way rejoicing. This same difficulty 
has occurred to me time after time, in the case of 
country churches having small burial-grounds shut in on 
every side by foliage. From no point can a view of the 
building be focussed on the glass except by using a lens of 
very short focus. Very often the conditions are reversed, 
and the photographer finds himself before a scene with some 
obstacle in front of him which forbids nearer approach, 
and the image on the focussing- screen is quite insignificant. 
Here the obvious course is to-screw off the front lens of his 
combination, and to treat the back one as a long-focus 
single lens. Of coarse, the camera must be extended to 
double its normal length, and no amateur should possess a 
camera that will not do so, should occasion require it. 

The most experienced workers often obtain a negative 
full of brilliancy and delicate detail, but with a very thin 
sky, a sky so thin that if a lantern-slide were taken from 
it raw, so to speak, we should have in it a very good repre- 


sentation of a November fog. There are several ways of 
obviating this difficulty. In exposing it before the gas- 
flame it should, like all thin negatives, be taken several 
feet distant, so that the time of exposure may perhaps 
extend to twenty seconds or more. During this time keep 
the sky portion covered with a piece of card which has 
been cut in Vandykes all along the edge next the horizon, 
but do not keep it still, but in gentle movement. This 
plan gives a clear sky, with the effect of a slight haze over 
the horizon, an effect, I need hardly say, frequently seen 
in nature. Indeed, this hazy effect can often be extended 
to the landscape itself, with the most charming effect of 
atmosphere which an artist could desire. 

Another plan of treating a thin sky is to furnish it with 
clouds by the following simple method: Paste over the 
glass side of the negative a piece of white tissue paper. 
When this is dry, hold it up to the light, and mark upon it 
the position of the horizon and the outline of any trees or 
other objects which may appear against the sky. Now, 
with a stump and a black pigment (such a pigment for use 
with the stump is sold by most artists' colourmen, I do 
not know the name) rub in masses of cloud, taking care 
that their edges are ill-defined and fleecy. By this means 
a flat, tame -looking negative can be made to yield a beau- 
tiful picture. Any water in the composition can be treated 
in the same way, for it must be remembered that water 
reflects clouds as well as anything else. Where the sky is 
dense enough, but contains pin-holes or other blemishes, 
Bates's black varnish, painted on the plain glass side, is the 
best remedy; or the faults can be delicately stopped out 
by ordinary India ink on the film side. Where there is a 


large expanse of sky, the quickest method is to gum over 
it a piece of orange-coloured paper with a jagged edge. 

A lantern slide, otherwise perfect, will sometimes re- 
quire a little strengthening. I believe that the best 
method of intensification is that long ago published by 
Mr. England. Here it is : 

Mercuric bi-chloride (corrosive sublimate) ... | oz. 
Sal ammoniac ... ... ... ... ... \ 

Water 12 

(Dissolve, and mark " Poison.") 

The picture, after well soaking in plain water, is im- 
mersed in this mixture, in which it will first turn grey, 
and afterwards quite white if left long enough. The 
white stage should not be reached unless a very great 
additional intensity is requisite. Remove from the solu- 
tion, wash most thoroughly under a tap for three or four 
minutes, and immerse in the following solution, which will 
almost immediately turn the film to a brown black : 

Liq. ammonia-fort ... ... ... ... drachm. 

Water ... ... ... ... ... ... Bounces. 

Rinse under the tap, and the operation is complete. Many 
people object to the use of the mercuric salt, on the 
ground that it is unstable, and that the picture will ulti- 
mately fade. I have not found this to be the case if the 
washing operation be thoroughly carried out, but as a rule 
I should give an intensified film a protecting layer of 
varnish. Prevention is better than cure, and the amateur 
should endeavour to produce pictures that will require no 

When the lantern transparency is complete it must be 
mounted before it can be considered out of hand. It is as 


well to try it in the lantern first, in order that any little 
blemish not before detected can be remedied. Any little 
clear spot where a clear spot has no business to be can be 
touched with India ink. If the picture is to be coloured, 
the slide need not be so firmly bound up as one to be used 
plain. A cover glass, separated from the photograph by a 
paper mask, with a round, square, or cushion-shaped open- 
ing, and fastened with one or two slips of gummed (stamp) 
paper, is quite sufficient until the artist is ready with his 
palette and brushes. But if the slide is to be exhibited as 
a plain photograph, it may as well be bound together as it 
is to remain. For this purpose we require slips of gummed 
paper fourteen inches long by three-eighths of an inch 
broad. The paper (black needle paper is the best) should 
be gummed before being cut, and one sheet will provide 
for about a hundred pictures. Mix powdered gum arabic 
with one fourth its weight of loaf sugar, and add sufficient 
water to make a thick mucilage. Paint the paper liberally 
with this, and hang it up to dry. When dry it can be cut 
into slips of the above size. 

To mount a picture, damp one of the slips of gummed 
paper, and put it sticky side upwards on the table before 
you. Now take a slide, duly fitted with its black mask, and 
a cover glass, all perfectly clean and free from dust. Hold 
the combination tightly between the fingers, and bring one 
edge down on the end of the gummed slip. Now treat the 
slide as a porter treats a heavy box, turn it over and over 
along the slip of gummed paper, so that each edge will 
take up its quantum. Now carefully fold down the edges, 
neatly adjust the corners, and the thing is done. 


The black masks can be bought ready cut at about three- 
pence the dozen, or the worker can cut his own if he prefer 
it. Zinc patterns are sold for this purpose, together with a 
clever cutting tool, which consists of a little steel wheel set 
in a handle (see fig. 43). The pattern is placed above the 

FIG. 43. 

paper to be cut, the little wheel is run round the opening 
in the zinc, and a cleanly cut mask is the result. A sheet 
of glass is the best bed upon which to lay the paper when 
cutting it. The gummed slips can also be bought, but 
those who prefer to be self-dependent will make their own 
in the way described. 

Not long ago I compared one of my slides with a wet 
plate one taken from the same negative by a first-rate 
operator, who is used to this class of work, and hardly 
does anything else. He was bound to admit that the 
gelatine picture was the better of the two, and said that he 
should think of relinquishing his bath after seeing what 
gelatine plates could do. I advised him to do no such 
thing. A wet plate is so certain in its results, that an 
unskilled hand, if he be furnished with the materials, can 
produce picture after picture without difficulty. I cannot 
say the same of gelatine plates, for they are such ticklish 
things that oftentimes something or other will go wrong. 


But for the amateur worker, to whom a few failures are 
not of any great moment, gelatine plates are best adapted. 
The silver bath, with its concomitant stained fingers and 
spoiled linen, is, I think, best left alone, unless the ama- 
teur adopts it as a necessary part of his photographic 

Those amateur photographers who are used to the work- 
ing of bromide paper, can produce lantern slides by an 
easier method than any of those just reviewed, namely, by 
means of the transferro-type paper which has lately been 
introduced by the Eastman Company, and with which 
many succeed in producing very fine lantern slides. This 
paper is coated with identically the same emulsion as that 
employed in the well-known bromide paper, and therefore 
the amateur has an advantage at the outset, of working 
with a medium to which he is accustomed ; its develop- 
ment being the same as that of the ordinary bromide paper. 
It consists of an insoluble sensitised emulsion which is 
applied to paper having a soluble substratum of gelatine. 
The tissue is exposed under a negative to gaslight for 
the requisite time, and according to the density and 
other peculiarities of the negative in question ; and is then 
developed in a ferrous-oxalate solution in the ordinary 
manner. It is then transferred to a piece of plain glass, 
which should be free from bubbles and other blemishes, 
while wet, being placed face down on the glass, and 
squeezed into contact. As much moisture as possible is 
then removed by the application of blotting paper. In 
about half an hour it will be ready for stripping ; but may 


be left if preferred until the tissue is quite dry. The glass 
and its print is placed in a dish containing water at 
the temperature of about 110 degrees if the print is wet; 
but should the print have been allowed to dry, the water 
must be some 10 degrees hotter. After allowing it to soak 
for a couple of minutes or so, the paper is raised at one 
corner, taking every precaution not to injure the sur- 
face; when it will readily separate from the film. The 
plate bearing the picture is then put into a solution of alum 
for a minute, and is placed in a rack to dry. Upon ex- 
amining a lantern slide so made, a slight granular appear- 
ance is observable in the high lights and the sky ; but this 
is not apparent when the image is projected on the lantern 
screen. The picture will have the usual grey tone, which 
is associated with f errous-oxalate development ; but it can 
be turned to a rich brown by the following treatment : 

. ( Potassium ferricyanide ... ... ... 100 grs. 

(Water 24 ozs. 

T, (" Uranium nitrate 100 grs. 

15 (Water 24 ozs. 

Take equal parts of A and B and immerse the print in 
the mixture until the tone changes to the tint required. 
Then wash thoroughly and immerse for five minutes in a 
freshly made-up solution hypo, three ounces ; water, six- 
teen ounces, wash. The prints that will best yield to this 
after-treatment are those in which the image is from any 
cause rather weak ; for this final bath not only alters the 
tone, but acts as an intensifier. 



giving directions for colouring lantern trans- 
parencies, I am quite aware that many persons 
will say at the outset that a good photograph is 
better without any colour at all ; on the principle, I suppose, 
that " good wine needs no bush." 

I quite agree with that opinion, and in colouring a trans- 
parency of good quality, I should be inclined to describe 
the operation more as tinting ; for the common method of 
colouring by which photographs are blotted out and 
drowned in a mass of pigment is simply atrocious. I 
lately saw a photographic transparency for a lantern, which 
was very beautifully and tastefully tinted, evidently by an 
artistic hand. 

The owner of this picture saw no beauty in it, but com- 
plained to me that he paid a long price for this thing, and 
there was hardly any colour on it, just as if payment ought 
to go by the amount of pigment stuck on the glass. 



In the first place, the worker must consider which of 
his pictures will be benefited by a coating of colour, 
for some subjects are very much better left alone, 
and shown as untouched photographs. This is especially 
true of such pictures as exhibit a mass of detail entirely 
covering the glass ; a woodland scene, for instance, with 
tangled masses of branches and underwood, and ferns in 
profusion. On the other hand, if the subject be an open 
landscape, with more than half of it consisting of white 
sky, it is undoubtedly improved by being tinted. The 
white sky receives, with great benefit, its natural tint of 
blue, relieved by masses or feathery tufts of clouds, 
which, if carefully introduced, can be made to look very 
like the real thing. 

In the directions that I am now about to give, it may 
therefore be taken for granted that all colour is to be put 
on most sparingly, and that its' amount must not be suffi- 
cient to obliterate the least detail in the photograph. Of 
course, if a bad photograph is to be coloured instead of 
being thrown into the dust-hole, which latter is by far the 
better course, colour can be piled on to it to hide its 
inherent defects, but this is only justifiable when the colour- 
ing is a necessity, and there is no time to procure a better 

Let it be understood that this work of colouring lantern 
transparencies is not easy. It not only requires a steady 
hand and good eyesight, but it wants artistic perception 
also, at least, to do it well. I do not say that a knowledge 
of drawing and painting is absolutely necessary to the slide- 
painter ; but it is certain that he who understands the use 


of any kind of colours, and has some knowledge of the way 
in which they can be combined to form different tints, will 
paint a slide very much better than one who is without 
that knowledge. Should he be quite unused to working in 
colour, he had best begin by procuring some book upon the 
general theory of colouring, so that he may understand the 
difference between a primary, secondary, and tertiary tint, . 
and may learn how to combine them together. There are 
plenty of such books to be had, and very often the infor- 
mation is comprised in some of those useful little manuals 
on water-colour painting which can be had of most artists' 
colourmen. I say water-colour painting advisedly, for the 
art of slide-painting partakes more of that kind of art than 
any other ; for the reason that it deals with transparent pig- 
ments. But do not let it be imagined that I recommend 
vvater colours for the work in hand. I know that some 
writers have advised their use, and there is more than one 
nanual which describes how slides can be painted in water 
colours. The process may possibly have answered under 
the old conditions, when the majority of lantern slides Were 
made by the wet process, and when the artist had a layer of 
collodion to paint upon. But most of my readers will wish 
to colour their own productions ; and as these will probably 
consist of gelatine pictures, which any application of water 
will blister, I will at once reject that method of painting as 
being inadmissible. 

First, I will make a few remarks with regard to the 
apparatus required, which is of the simplest description. 
A retouching desk will make a good easel (see fig. 44), or, 
failing this, one can readily be made by using a sheet of glass- 
L 2 


in a frame. A small school slate measuring about 8 by 5, 
with the slate knocked out, and a piece of window-glass put in 

Fig. 44. 

its place, makes a very good easel for slide-painting. This 
should be hinged on to a base board with a strut at one 
side, so as to keep it at a convenient slope for working. A 
sheet of white paper placed on the base board at the back 
completes the arrangement. 

Beyond the easel we shall require a palette, and a white 
tile answers the purpose as well as anything else ; some 
brushes, a few colours, a sheet or two of white tissue paper, 
and a piece of linen cloth upon which to wipe the brushes. 
One or two bottles containing different media will complete 
the list. The colours employed are those used by artists 
for oil painting, and which are enclosed in collapsible metal 
tubes. But, unlike the oil painter, the lantern-slide artist 
Is confined to the use of those colours only which are 
naturally transparent. To make this clear, let us suppose 


that any one ignorant of the subject were to attempt 
to use such a colour as vermilion, which is opaque ; it 
would appear to be of the usual vivid scarlet when seen on 
the glass, but seen through the glass, it would simply be a 
black patch, because the light cannot filter through ik 
This being the case with all the opaque colours, we there- 
fore discard them. I now annex a list of colours which are 
at the disposal of the slide-painter, and which are all more or 
less transparent. They are not all actually essential, but 
still the artist will do well to procure them, as they will 
give him an immense variety of tints : 

Prussian Blue Brown Madder 

Indigo i Rose Madder 
Italian Pink Purple Madder Af 

V" Raw Sienna v/ Crimson Lake 

V^ Yellow Lake Ivory Black 

Chinese Orange \ Burnt Sienna 

,/ Neutral Tint McGilp. 

\f Brown Pink 

It will be noticed that there is only one brilliant blue in 
this list, that is Prussian blue. For landscape work this 
blue is used, perhaps, more than any other colour ; for skies 
always, and it enters into the composition of the various 
greens, and forms useful tints with most of the other pig- 
ments. It is not the colour which an artist would choose by 
preference with which to depict the tender tints of the sky, 
for, truth to tell, it has a greenish hue, and is rather cold 
and repellent in character ; but it is really the only blue 
which can be laid on the glass in a flat, even tint, and 


therefore we must make the best of it, such as it is. We 
have a far larger choice in yellows, for no less than four of 
the colours quoted are, in spite of their names, yellow in 
tint. These are Italian pink, the most useful of all 
Raw sienna, not nearly so pure a colour ; Yellow lake, 
rather a difficult colour to work with ; and Chinese 
orange, a most valuable and rich tint. Brown pink may 
also be described as a yellow, and brown madder has also a 
great deal of the same colour in its composition. The reds 
represent a great difficulty to the slide-painter, for, although 
they appear to be very rich when spread on canvas, they are 
very weak colours when we come to look through them in 
a transparency. It is next to impossible to produce a real 
scarlet as a transparent colour, but the nearest approach to 
it can be made by using Chinese orange mixed with crimson 
lake. A great variety of browns may be obtained by com- 
bining burnt sienna with the other colours, and the ivory 
black will be found most useful in this service. The best 
brushes for general work are those of camel-hair, which 
have the further advantage of being cheap. But a few 
sables will be wanted for delicate markings. 

A thing of first importance is the selection of a suitable 
medium with which to mix the tints. Canada balsam in 
turpentine is of great value. Another good one, which I 
believe many slide-painters use almost exclusively, is made 
by diluting copal varnish with turpentine, while for dark 
colours, japanners' gold size, diluted in the same way, is an 
excellent medium, and is of special use in the foreground. 
The colour should ba mixed up on the palette with the 
medium selected with a proper palette-knife, so as to form 


what is in reality a coloured varnish ; and this must be 
quickly applied to the picture before it has time to thicken 
by evaporation of the solvents. 

For greens, to be used mostly in foliage and for grass, 
yellow and blue must be mixed together in varying pro- 
portions. There is no such thing as a satisfactory trans- 
parent green which can be bought ready made, and suit- 
able for the purposes of the slide-painter ; but the use of 
the two colours named, if we take care to vary the pro- 
portion of each, can be made to give a great variety of 
tints. But it should be pointed out that, if used alone, this 
compounded green will be far too raw, and will exhibit a tint 
which is never seen in nature. 

We mix, therefore, with the yellow and blue, some red 
or brown, to take off this rawness. An endless variety of 
tints may be made by taking three colours only, and using 
them in different proportions, and I would advise the slide- 
painter to mix some of these tints, and put them side by 
side on a bit of glass, with a ticket attached to each 
describing their constituents. This specimen glass will be 
useful for future reference. I give in the next chapter a 
few compound tints, which can be made easily, and can be 
used for foliage, etc. 

The list of colours given will be found more than 
sufficient for all needs, and many slide-painters do very 
good work with only half their number, for there is no 
limit to the number of tints which one may get by 
judicious blending. Mathematicians are able to tell us 
the number of chances against a whist-player turning 
up the same cards on two different occasions, and we 


know very well that the odds against such an occurrence 
amount to an enormous figure, but no mathematician 
would be able to calculate the number of different tints 
that we can procure, even from the three primary colours. 
We have such tints in the beautiful solar spectrum, 
but there they blend into one another so gradually that 
no eye can count them. 

One of the great helps to success is to observe the rule of 
being very sparing of both colour and medium when dab- 
bing in the sky portion of the picture ; but the painter can 
be more lavish with both when he is dealing with foliage, 
and any broad masses of light or shade.* Here he can 
often use a large camel-hair brush, and can mop in the 
colour, only taking care that he does not go over the out- 
line which circumscribes the particular portion of the 
picture he is working upon. In the case of a mass of foliage, 
let him mix up the desired paint on the palette with a 
flexible palette knife, which he should always have at hand. 
This should be done thoroughly and quickly ; then let him 
take up a moderate quantity of this colour in the brush and 
mop it on to the surface of the picture. For this class of 
work mastic varnish, very much thinned with turpentine, 
forms a capital vehicle. The .strength of this mixture may 
be one part of mastic to six of turpentine. This medium 
keeps liquid long enough for careful manipulation, and yet 
it dries quickly in comparison with other media which 
might be named. 

Photographic transparencies are now produced of such 
varied tones that in many cases it will be found advisable 
to leave portions of the picture quite uncoloured. With 


chloride plates especially a very wide range of tones can be 
obtained, and practically the experienced worker can pro- 
duce a picture in any colour, from black, ranging through 
different changes of brown, to red ; and even a blue picture 
can be produced on that type of plate. It is often prac 
ticable to suit the tint to the class of subject. A woodland 
scene may be toned a rich brown, for example ; and this 
tone, which the picture possesses at the outset, will prove 
of great help to the colourist. Many water-colour painters 
commence their work by giving the surface upon which 
they work a yellow-brown tint, and, when that is dry, they 
commence the picture proper. It will be readily seen that, 
with a photographic picture toned in the way described, the 
slide-colourist will work under much the same conditions. 
The object in both cases is to give a general warm tone to 
the picture, which cannot be blotted out even by the most 
careless and ignorant worker. 

It is a good practice to examine the slide in the lantern 
as the various stages of the painting progress, taking care 
to protect it from dust. For this reason it should, before 
being placed on the lantern -stage, be furnished with a 
paper mask and a cover-glass ; it may then be slipped in 
a mahogany frame kept for the purpose. By this exami- 
nation under the light by which it is ultimately to be 
shown can we alone judge of its defects. It is now that 
the dust, previously invisible, becomes painfully evident. 
The beginner will, indeed, be forced to acknowledge that 
this is an example of matter in a very wrong place. He 
sees up in the sky of his landscape, which he just now 
thought would look so very beautiful, what is apparently a 


broomstick ; but careful examination shows that it is only 
a little piece of hair about a quarter of an inch in length, 
which is magnified into the size of the useful domestic 
appliance just mentioned, and, what is more, these little 
bits of hair are very difficult to remove. We may per- 
haps; lift them with our etching-needle from the paint in 
which they are embedded, but in doing so we are pretty 
sure to leave scratches behind which are almost as bad as 
the hairs. Bits of dust are everywhere, and the only way 
in which their intrusion upon our work can be avoided is 
to devote a room to this express purpose of slide-painting. 
It should be uncarpeted and uncurtained, and should be 
swept with tea-leaves, or better still, with damp saw-dust, a 
few hours before any painting is attempted. Its table and 
only chair should be wiped down with a damp duster, and 
the same treatment should be applied to the window ledge, 
or any projecting parts of the wood-work which may be 
near the painter as he sits at his work. The artist should 
put on a linen blouse, which is rigidly kept for this work. 
All these precautions may seem unnecessary, but we must 
observe them if we want to produce the best possible work. 
I have seen slides, otherwise well executed, which were 
quite spoiled by dust, and it is one of the aggravations of 
the slide-painter's life, that dust always gets into the sky, 
where, of course, it is more evident than in any other por- 
tion of the picture. 

Let the table upon which the operator works be placed 
near a window, preferably under a north light. This 
table should be wiped over with a damp duster imme- 
diately before the work is commenced, and it should be 


covered with a sheet of newspaper, also wiped with the wet 
cloth. The easel is put in the front centre of the table ; 
on its left-hand side may be placed the colours, while on 
the right the palette must be within easy reach, together 
with a sheet of tissue-paper folded in four, so as to make a 
kind of pad upon which to wipe the brashes. The medium 
employed varies with the particular colour which happens 
to be in .use, but turpentine forms the basis of all. A 
little cup of turpentine should stand close to the palette, in 
which the brushes can be washed, previously to being 
partially dried by being stroked gently on the pad of 
tissue-paper before mentioned. 

Supposing that the picture upon which the operator tries 
his 'prentice hand is a landscape, the sky will be the portion 
of the slide which will first require his attention. Squeeze 
out from the Prussian blue tube a little bit of colour about 
the size of a grain of wheat, for this tint is so powerful 
that a little of it will go a long way. Near it place a little 
McGilp. Now dip one of the brushes in the turpentine, 
mix it on the palette with the McGilp, and with sufficient 
colour to give the strength of tint desired. Now paint 
over the sky portion of the picture with bold, even strokes, 
from side to side. The brush will leave plenty of markings, 
ugty ridges from right to left ; but let these pass for the 
present, for we shall remove them in the next stage of 
the process. The picture should remain as it is for a 
minute or two, so as to give time for the turpentine to 
partially evaporate, when we must proceed to the 
operation of dabbing. Dabbers are made of different 
materials ; sometimes it is recommended to use a piece of 


fine wash-leather, formed into a little ball by cotton wool 
inside, tied up like a small pad. I have not found such a 
dabber to be satisfactory in practice ; for the leather, how- 
ever fine, leaves feathery marks upon the colour, which, 
although they are not readily seen on the slide, become 
painfully evident when the picture is magnified on the 
screen. I myself tried, a short time ago, to make some 
special dabbers for this work, which were composed of 
gelatine and glycerine moulded in a small cup like an egg- 
cap. These dabbers, also, were not as satisfactory as I 
could have wished, although I found that they were better 
than those of wash-leather. The best dabber which it is 
possible to get is the finger. This needs a certain amount 
of preparation. The flesh of the finger is covered with a 
number of little ridges, which we well know make what 
we call finger-marks on anything touched. These ridges 
can be obliterated by rubbing the finger with pumice-stone 
and water, or by using the pumice-stone soap, which is 
sold for the express benefit of much-soiled hands. A 
quicker plan is to rub the finger a few times on very fine 
glass-paper, when the ridges quickly disappear. It is 
obvious that the operation of rubbing down must only be 
carried to a slight extent, or "else soreness will result. The 
finger makes a far more perfect pad than any artificial con- 
trivance because of its exquisite sensibility ; for in using it 
we both see and feel the progress of the work. 

Commencing at the left-hand top corner, we dab with 
the finger rapidly from side to side of the picture ; at first 
it will make ugly marks, but the turpentine gradu- 
ally evaporates as the work proceeds, and these marks 


blend into one another, until they finally disappear, and we 
have before us a flat, even tint of colour. The knack of 
laying in a sky cannot be gained without a great deal of 
practice ; but the operator may feel assured that when he 
has once conquered this initial difficulty half his labour 
is over. 

If we merely want a plain blue sky, and where the 
amount of sky is small it is often expedient that this should 
be the cas.e, we can consider this portion of our picture 
finished with the dabbing ; but if we want to indicate 
clouds, this must be done before the colour has commenced 
to dry. Here comes in the work of the artist. From what 
I have seen exhibited in the shop windows, I conclude that 
many slide-painters classify clouds under two general 
heads, namely, large masses called "feather-bed clouds," 
and small ones, called " bolster clouds." These are created 
by means of a leather stump, moved with a semicircular 
motion, by which clouds of either pattern can be wiped 
out to order. The student of nature will, however, aim 
at something higher than this ; for he will know that no 
two clouds, of the thousands he has gazed upon, have ever 
been alike. For convenience sake, meteorologists write of 
cumulus, cirrus, stratus, and nimbus forms of clouds, but, 
in reality, although each term describes a typical form of 
vapour, they convey very little information to the mind's 
eye. Each form so constantly blends with the other to delight 
the eye, that no words can sufficiently describe the vast 
variety of cloud beauties presented to us. In attempting 
to imitate some of these effects of nature in glass-painting, 
I find that a piece of kid wrapped round a pointed stick 


is far more serviceable than an ordinary leather stump. 
The rough side of the leather should be used as the rub- 
bing surface, and, by altering its position on tbe stick, 
sometimes letting a soft ragged edge touch the paint where 
a fleecy cloud is to be described, and sometimes using the 
material tightly stretched over its support where bold 
touches are necessary, a great number of different effects 
can be secured. The sky being finished, it will be convenient 
now to put in any other parts of the picture where blue 
or purple is required. The distant hills can be covered 
with the sky tint, mingled judiciously with a little crimson - 
lake. Water, in which the sky is reflected, will, of course, 
be painted in with the sky colour. Shadows generally will 
also partake of the purple tint already mentioned. These 
are all laid in with the brush, as before indicated, and, time 
having been given for tbe partial evaporation of the turpen- 
tine, they; must be gently dabbed with the finger. No care 
need be taken about transgressing over other portions of 
the picture where blue or purple has no business to be. 
These can be wiped clean with leather or stump, after the 
tints have been satisfactorily laid in. 



SLIDES (continued}. 

GREAT many subjects can be advantageously 
treated as moonlight pictures, and very attractive 
they are if well done. In this case, the blue 
must be laid on of a much darker hue, and can have 
blended with it a little ivory-black. Having decided 
upon the best position for the " queen of night," that 
place should be lightened by extra hard dabbing, and 
any clouds that may be required can be wiped out at 
the same time, taking care that their light edges are 
nearest to the uncreated moon. The moon must not 
be wiped out, but must be picked out, film and all, so 
that nothing but bare glass is on the spot covered by it. 
To accomplish this, wait until the paint is bone dry, and 
attach to the place where the moon is to be a tiny piece of 
gummed postage-stamp paper. This should not be bigger 
than a small pea, and is merely for the temporary purpose 
of holding the leg of a small pair of compasses. I keep a 
special pair for this particular work, one leg being ground 


so as to form, a cutting edge. Having opened the compass 
to the required distance, plant one point on the paper, and 
gradually with the other cut through the gelatine film. 
The circular disc so marked out can now be quickly picked 
away, bit by bit, with the etching-needle. (This needle, 
by the way, is merely an ordinary needle, bound to a pen- 
holder by waxed thread.) The same instrument can be 
used afterwards for picking out effective lights in the fore- 
ground ; but the great fear is that the beginner should 
abuse the power thus put into his hands. The touches 
should be of the most minute description, and the operator 
should constantly remember that his work, with all its 
faults, has to be magnified to a very great extent. 

I need hardly point out that a most effective change can 
be made by showing a landscape, first coloured as a day- 
light picture, and then dissolving it into the same view by 
moonlight. This change requires a double dissolving-view 
lantern, the daylight picture being placed in one lantern, 
while the moonlight picture is placed in the other, care 
being taken that both pictures register; that is to say, 
occupy exactly the same position on the sheet upon which 
the images are projected. 

But let the beginner not attempt sunsets of the gorgeous 
order, after the manner of G. M. W. Turner (deceased), 
until great practice has taught him the different character- 
istics of his colours. I do not here allude to their tone 
character, but to the different ways they behave, mechani- 
cally, when applied to the slippery surface of the picture, 
and the different media required to coax them into lying 
flat. He may think that, because he knows how to produce 


a good even sky-blue tint, he has only to try the same pro- 
cedure with his yellows and reds to produce all kinds of 
brilliant, ethereal, striped-petticoat effects. But, on trying 
these colours, he will soon find out his mistake, and will 
also find that he must add varnish to them before he can 
work with them at all. Moreover, they seem to be espe- 
cially prone to attract any little unconsidered trifles in the 
way of dust which may be seeking rest. 

I was so impressed with these difficulties with regard to 
sunset skies, when first I began glass painting, that [ sought 
for another means altogether for gaining what I wished. 
I was attracted by the brilliant hues of the aniline, or coal- 
tar colours, and at once endeavoured to enlist them into my 
service. As others may be tempted to work in the same 
groove, I may at once state why, after patient trial, I dis- 
carded them. Most of these colours can be readily dissolved 
in alcohol, and, therefore, it is not difficult to make 
coloured varnishes with them. But when I tried to paint 
my gelatine picture with the splendid tints, I found it next 
to impossible to confine them within the boundaries of any 
outlines whatever. They would flow over the edges on 
their own account, do what I might. The fact is that these 
aniline colours have a kind of greedy affinity for gelatine, 
and there seem to be no means of controlling their advance 
when once they come into contact with it. By flooding 
an entire picture with a yellow or red varnish, I was able 
to gain (sometimes) some wonderful effects. But the action 
of the dye upon the gelatine was of too uncertain a nature 
to tempt me to adopt that method of working as a perma- 
nent resource. Lastly, aniline colours are fugitive. 



Hitherto I have regarded the picture as possessing a 
plain glass surface to represent the sky, and this will be 
found to be the case with most photographic slides. But 
we all know that a plain white sky in a photograph is, from 
an artistic point of view, an abomination. By the simple 
process of colouring we get over the difficulty ; still, if we 
can produce upon a photographic transparency natural 
clouds either existing in the original negative by the virtue 
of a properly-constructed shutter, which will only give a 
fraction of the normal exposure to the sky, or by a system 
of printing-in from a separate negative in a way that need 
not be described here, it will be a great artistic gain. In 
colouring such a sky the painter has a great advantage, for 
irregularities in laying on the colour, which would other- 
wise be distinctly visible, are hidden by the details of the 
clouds in the picture. 

In colouring such a sky we may commence, as usual, by 
dabbing on the blue in the spaces which represent rifts 
between the clouds, and we can then add tender tints made 
up by mingling such colours as crimson lake, and the 
various yellows at our disposal, and we can also add to the 
richness of the general effect by putting in different tones 
of lavender, mauve, and purple, made up with crimson lake, 
the madders, and blue. These colours, after the blue has 
been dabbed on, can best be painted in with the brush, 
using as a medium Canada balsam in turpentine. This is 
a good, quick-drying medium, and it has the advantage of 
being so pale in colour that it will not affect the most deli- 
cate tints. 

Before proceeding farther with the work, the picture 


should be dried by heat, and there are many means of 
doing this. An oven, not too hot, will do what is neces- 
sary, but it is uncertain, for the heat may rise to such a 
pitch that picture, gelatine, and all will curl off the glass. 
A tin biscuit canister, divided into grooves, and placed 
(dutch oven fashion) in front of a good clear fire is better ; 
but the best plan that I have tried is the following : place 
the glasses to be dried upon a flat iron plate above a gas 
stove, the heat of which can be regulated. Upon the top 
of the plate put a frame of wood, covered with fine muslin, 
to keep off the dust. About twenty minutes of such treat- 
ment will make the layer of paint on the glass so hard 
that it can be worked upon with other colours, or sub- 
mitted to the moonlight operation as already described. It 
is during the operation of laying in the sky, &c., which may 
be comprehended under the term " first painting," and the 
subsequent drying, that access of dust must be carefully 
guarded against. 

Lantern slides, by Whatever photographic process they 
may have been produced, will stand a great deal of heat, 
and they can be made hotter than the hand can con- 
venie,ntly bear with impunity. This heat may be con- 
tinued for about half an hour, and it will be found that 
it has a kind of japanning effect upon the oil colours 
employed ; indeed, the colours are by this means made so 
hard that it is difficult, if not impossible, to remove them 
afterwards without at the same time destroying the photo- 
graphic image beneath the pigment. 

After the sky has been dried in the manner described, it 
can easily be deepened, if found necessary, by the &pplica- 

M 2 


tion of a little more paint, which need not be applied with 
a brush, but can be simply dabbed on with the finger. 
Some very good effects are often possible by this second 
painting, especially when the sky is. deepened, in the 
manner described, at its upper part or zenith ; such a 
deepening, it will be readily seen, being in strict accordance 
with the sky of nature. 

A blue sky with white clouds formed by the simple 
operation of wiping out the colour, and leaving the clear 
gelatine, is by far the easiest kind of sky to produce. It can 
be modified in various ways by working other colours upon 
it near the horizon, such as red or black, most sparingly 
bestowed, or the zenith tint can be strengthened after the 
slide has been dried. A most effective sky is that which I 
may call the ordinary summer twilight sky, that is to say,^ 
the deep blue at the zenith, fading gradually to a lighter tint 
until it merges into bright yellow or orange at the horizon. 
Such a sky is not difficult to produce. The best way will 
be to commence at the horizon by dabbing, without the 
use of the brush, Italian pink on to the glass ; a very little 
colour being applied to the finger, with the addition of the 
merest trace of medium, such as Canada balsam, in turpen- 
tine. This must be diligently dabbed upon the glass until 
its stickiness almost disappears, and its upper margin is 
left without any hard lines. Then the finger should be 
washed in the cup of turpentine which the painter should 
always have at his elbow, and the blue may be applied to the 
upper part of the picture in the ordinary way, and dabbed 
down until it almost touches the yellow which has been 
previously laid on. Once more wash and dry the dabbing 


finger, and then use it, without any fresh application of 
paint, to merge the two colours into one. In this way 
it will be found, after a little practice, that a good junction 
can be made, and that one colour will exhibit a regular 
gradation into the other. If this work is well done, the 
effect will be found to be a most pleasing one,, and should 
not be meddled with by the addition of clouds. 

Our painting has now progressed to a certain stage. The 
sky has been laid in, the clouds have been wdped out, and 
the shadows have received a delicate purple tint. The 
whole has been submitted to a baking operation, by which 
the attached colours are made so hard and firm, that it 
would be difficult to remove them without destroy ing at the 
same time the gelatine film upon which they are superposed. 
We now place this unfinished sketch again upon the glass 
easel, and will endeavour to turn it into a finished picture. 
It is at present what Mr. Whistler would call " an arrange- 
ment in purple and blue." We will endeavour, by working 
over these tints where required, and by adding others, to 
produce a general harmony of effect, as nearly approaching 
to nature as possible. 

Any one possessing artistic feeling, and no one without 
that faculty will make a really good slide-painter, although he 
may easily come up to a common standard, will, on first 
looking at the subject for colouring, make up his mind as 
to the way in which he means to treat it. He will arrange 
to have a cloud mass in one place, possibly to relieve a 
church steeple or other high building, or a bright horizon 
where, possibly, lights are to be seen through tangled 
masses of foliage ; or in other ways he will have in his 


mind a definite programme to follow out, and will do his 
best to achieve it, and will do so with more or less 
success. But, through all, he must bear in mind that his 
picture will eventually be highly magnified, and that the 
least blemish will be magnified too. In no art, perhaps, 
can a man learn more by repeated failures (failures 
which should be, from time to time, submitted to the 
searching light of the lantern) than he can in this art 
of slide-painting. 

The worker must constantly remember that the effective- 
ness of his picture is dependent far more upon contrast 
than upon the tone of any particular tint. Without con- 
trast his colours will be meaningless and poor, although, 
individually they may present brilliant hues. The rule 
governing contrast of painters' colours, i.e., colours which 
are complimentary to one another, is most simple. Here 
it is in a nutshell. The three primary colours are red, blue, 
and yellow.* Any two of these mixed together form a 
secondary colour which is complimentary to the remaining 
primary. For example : Red and blue mingled form 
purple. What better contrast to purple can there be than 
yellow, its complimentary, being the primary which is 
left out of the combination ? * Again, blue and yellow form 
green, and green is complimentary to red. Once more, 
yellow and red form orange, the complimentary of blue. 
I have no hesitation in saying that a man possessing this 
little bit of elementary knowledge is far more likely to 

* This is not correct for coloured light, but answers for painters' 


produce an effective picture with three colours than can 
one ignorant of it, although he may have the run of all 
the artists' colour-shops in the kingdom. He can never go 
far wrong if he will, so far as the subject will allow, place 
green against red, orange near blue, and yellow in conjunc- 
tion with purple. A subject, such as an Oriental street- 
scene or bazaar, where such combinations can be made 
without stint, has a most gorgeous effect when projected 
upon a screen. Each of these colours can at the same time 
be mingled to give an endless range of tints, in fact, all 
the colours of the rainbow. And now let me give a few 
hints as to finishing colours and combinations useful for 
special purposes, together with the best media with which 
to mix them. In these finishing colours the dabber, except 
in extreme cases, must be relinquished, and the brush 
(camel hair and sable) alone employed. 

Skies and Clouds. Prussian blue (some prefer Chinese 
blue), rose madder, purple madder, Italian pink. The blue 
to be laid on as already described, using as a medium 
McGilp and turpentine. In laying on after tints a small 
quantity of copal varnish should be added. 

Water always reflects the colours above it. If the water 
be very still, the effect of surface may be given to it by 
drawing gently across it a dry (mop) brush, such as gilders 
use. In brooks and running streams, lights may be picked 
out while the colour is wet, with a pointed stick, or when 
dry with the etching-needle. In representing rough sea, 
we must remember that such water not only reflects the 
colour of the sky above it, but shows also its local colour. 
It may first be painted over with the sky colour, and, after 


baking and drying, this can be worked upon with various 
shades of yellow, blue, brown madder, and indigo ; medium 
Canada balsam varnish, McGilp, and turpentine. 

Boats and Shipping. Black, raw sienna, Vandyke 
brown, burnt sienna, Chinese orange, indigo, indeed, 
nearly all the colours available. Medium, same as last. 

Foliage. For foliage we are limited for our greens to a 
mixture of Prussian blue and the various yellows, namely, 
Italian pink, raw sienna, and brown pink. But these will 
give endless variety of tones, particularly when aided by 
other colours. Here are a few examples : 

Blue, Italian pink, and burnt sienna. 

Italian pink, Vandyke brown, and indigo. 

Italian pink and brown madder. 

Brown madder, Italian pink, and indigo. 

By adding Chinese orange to any of these, autumnal 
effects are readily obtained. Media, Canada balsam var- 
nish ; and for the darker colours, gold size. N.B. These 
various combinations should be made up on the palette, 
as required, with the help of the palette knife. 

Foreground. It is here that the artist can employ all 
the treasures of his palette. Let him remember that any 
particular colour can be easily modified by glazing another 
colour over it. This is done after the first colour is dry 
by mixing a second tint, which may be applied above it. 
The medium for this varnish will vary with the glazing 
colour employed. Canada balsam will do for most, but 
where reds are used, which are slow driers, the medium 
should be gold size. 

Let the painter ever remember that force of colour can- 


not be obtained by piling on masses of pigment, which will 
naturally serve to obscure the details of the photograph 
upon which such pigment is placed ; but this force of 
colour can be easily produced by judicious contrast of differ- 
ent tints. As I have before observed, the student must 
make himself master of the art of colouring, if possible, 
before he commences its practice. Some years ago there 
was published an excellent series of little books, costing 
only a few pence each, giving chromo-lithographic examples 
of various simple studies in water-colour painting by 
Callow and other artists, under the title of " Vere Foster's 
Drawing Books." These books, I believe, are still to be 
had, at least, I hope so, for they are full of merit, and 
give more valuable instruction than many works of far 
more pretension. They give specimens of water-colour 
sketches, unfinished and finished, side by side. Perhaps 
the former are the more valuable for our present purposes, 
for they exhibit merely broad masses of colour, and show 
how one tint can be made to contrast with another. It 
will be seen in some of these pictures that a blue sky is 
contrasted with orange yellows in the landscape beneath 
and how, on the other hand, a yellow sky can be rendered 
at once effective by purple hills upon which it seems to 

When the picture is entirely finished, it may be once 
more submitted to the baking operation, taking care that 
the heat never rises to blistering point, or all the labour 
spent on the slide will be thrown away. The picture may 
now again be placed on the easel, and if the artist has 
sufficient reliance upon his power of knowing when to stop 



he may with advantage take up the etching-needle ; some- 
times a single touch of this magic wand will much improve 
a picture. In forest scenery, for instance, a light on a 
trunk, or on a protruding branch, will make the one or the 
other to stand out almost stereoscopically. Now and then 
too a little spot or two may be picked out of the foliage 
itself. But not in the manner I lately saw in an exhibited 
slide, where curly lines, after the drawing-master style of 
former days, were made to describe the edges of the trees 
in every direction. This was actually perpetrated upon a 
good photograph, and represents the worst instance of 
" painting the lily " which I have had the misfortune to 
come across. 





|OB different experiments, various forms of slides 
must be employed. The galvanometer slide, 
shown at fig. 45, is an extremely useful 
one for demonstrations in electricity and magnetism. 
I need hardly mention that such a slide consists of 
a magnetised needle, which is surrounded by a coil 

FIG. 45. 

of fine wire. This coil is flattened, and there is just 
space enough between its convolutions for the needle 
to move from side to side. It is supported on 


a central pin, which is shown by the screw slit in the cut. 
A pane of glass of a semicircular shape forms a back- 
ground for the needle ; and this glass can either be left 
plain, as in the illustration, or it can have drawn upon it a 
scale. The slide figured is without the arrangement just 
mentioned, and it is one that I have employed for a special 
purpose. I have used it as a means of demonstrating the 
action of the needle telegraphic instrument ; and it will 
be noticed that two little buttons are fastened to the 
glass in order to prevent the needle making too wide an 

It may be mentioned here for the benefit of those who 
are unused to electrical instruments, that a galvanometer 
furnishes the means of detecting the existence of an elec- 
tric current. In its higher forms it is so sensitive that 
a current, generated by touching two dissimilar metals 
with the fingers and excited by the natural warmth of the 
hand, can, by a galvanometer, be made evident to the eye. 
The most simple form of galvanometer can be readily 
made from one of those little charm compasses which are 
sold at the opticians' for about Is. each. Take such a 
compass, and bind it across with several layers of fine silk- 
covered copper wire. Place it in such a position that the 
wire coil lies parallel with the needle, which will, of course, 
be north and south ; now join the ends of the wire to 
any form of electric battery, and the needle will imme- 
diately swing round and take an east and west direction. 
By changing the position of the wires with regard to the 
poles of the battery, it will be noticed that the needle is 
deflected in the opposite direction. These phenomena 



FIG. 46. 

form the basis of the single needle electric telegraph, and 
it is to demonstrate the powers of that telegraph that the 
lantern galvanometer, which 
is here figured, has been 
devised. It will be noticed 
that on its right-hand side it 
is furnished with two ter- 
minals. These are connected 
with the ends of the coil 
wire, and provide a means of 
readily joining the instrument 
up to the battery, placed in 

any position outside the lantern ; but in practice it will 
be found advisable to also place in connexion with this 
slide and its battery a little piece of apparatus which may 
be called a "current reverser," which can easily be made 
at home. It is shown in fig. 46. It consists of two 
little treadles formed out of brass. This brass, it may 
be mentioned, should be of the hard-rolled kind, such as 
is used for springs. 

Each of these little treadles is fastened down to a maho- 
gany board, which forms the base of the instrument, and 
each one is in connexion with a terminal screw, which is 
indicated in the cut by a round dot. Across the other end 
of the treadles is a raised bar of brass, against which they 
spring up and touch when in their normal condition ; but 
when either of them is pressed down, it touches a piece of 
brass wire which is let into the top of the mahogany board 
immediately underneath. 

This wire, as well as the piece of brass just mentioned, 


is connected with its own terminal ; these two latter ter- 
minals in the cut being lettered bb, and signifying that 
they should be joined up to the battery employed. The 
other two, which are lettered gg, are fastened to the 
terminals on the galvanometer slides. 

In practice it is best for the current reverser to be placed 
on the lecturer's desk, at some distance from the lantern, 
while the galvanometer slide is joined up by means of tem- 
porary wire connexions. The lecturer then has the power 
of reversing the current by touching with his finger either 
of the two treadles, and he can demonstrate in the most 
perfect manner how the different letters in the tele- 
graphic alphabet are made up of movements of the needle 
to the right or left, as the case may be. He can also point 
out that the " dots " and " dashes " of the Morse system 
correspond with these right and left hand movements of 
the magnetic needle. 

In the old days of the Polytechnic Institution in Regent 
Street, which was the resort of so many delighted schoolboys 
and girls, there were several experiments performed with the 
lantern which, so far as I know, have not been repeated 
elsewhere. One of the most curious was the movements of 
the legs of a frog. This is rather a difficult experiment to 
perform, but when well done, is highly effective on the 

At the Polytechnic the frog's legs covered the large 
screen, and were thus magnified to about 26 feet. The legs 
were hung to a special form of slide, and the nerves and 
muscles of the dead frog were touched with metallic wires, 
when they immediately kicked out in the most startling 


manner. The importance of this experiment, as a demon- 
stration, will be acknowledged when it is remembered that 
this movement of a frog's legs, accidentally brought about 
by Galvani, laid the foundation of our present knowledge of 
current Electricity or Galvanism, as it used to be called, 
after that first experimenter. 

Another most effective experiment was shown in con- 
nection with a lecture upon the Suez Canal by Professor 
Pepper. After exhibiting a number of experiments upon 
sand, and showing that it always fell at a certain angle, 
and exerted lateral instead of perpendicular pressure, 
an image of an ordinary hour-glass was cast upon the 
screen. This sand-glass was supported in a frame, and its 
sides were flattened so that it could fit the lantern stage. It 
had rather an amusing appearance, because like all instru- 
ments placed in the lantern, the image was inverted, and 
the sand therefore appeared to flow upward instead of 
downward. A curious fact, too, was noticed when this 
familiar instrument was magnified to such an enormous ex- 
tent, each particle of sand was seen to strike a blow upon 
the top of the cone above, and the force from that blow 
passed from the point of the inverted cone to its base, and 
formed a peculiar wave -like figure in its passage. 

I have never seen this experiment repeated elsewhere, 
but it is one that should not be forgotten. 

Among the experiments which can be performed by 
means of a lantern, and better performed, so far as an 
audience is concerned, than by any other means, are 
those relating to cohesion figures. Professor Tomlinson 
was the first to give much attention to these interesting 


figures, and he made many experiments in this direction. 
He found that almost all the common oils and fats give 
natural diagrams by which they can be identified ; and 
further, that these figures will vary, according to the length 
of time for which the oil has been exposed to the air. To 
get some idea of the nature of these beautiful figures, a 
drop of pure sperm oil may be allowed to fall on the surface 
of a pan of water. It will be seen in a few seconds that 
the film of oil will break up into a number of little open- 
ings, and that it will exhibit a pattern of great beauty. 
Rape oil, Lucca oil, and some others, give patterns of en- 
tirely different designs ; some of them very much resembling 
beautiful crochet- work. In order to show these patterns 
in the lantern, we have two or three different methods of 
going to work. We can exhibit these cohesion figures, for 
instance, by the simple aid of two pieces of clear glass. 
Between two such plates put a little vaseline, which in 
order to increase the effect on the screen may be coloured 
red with alkanet root. The plates are pressed together, with 
the vaseline between them, and are then secured by a ring of 
india-rubber at each end. They are then put into the lan- 
tern, and while standing upon the lantern stage the blade 
of a knife is inserted between the two glasses and gradually 
turned so that they are slightly separated. The effect 
upon the screen is very beautiful, the disc appearing to be 
covered with arborescent figures. This experiment may be 
repeated more than once, but the vaseline will require 
renewal after a time. Another mode, and perhaps a better 
one, of showing the same phenomena, is by means of the 
vertical attachment to the lantern. In this case the 


lantern slide must take the form of a shallow box, having 
a glass bottom. Such a box can easily be made by fit- 
ting a piece of thin glass, say, 3J inches square, into 
a frame of wood half an inch in height, and cementing 
the glass in a groove with marine glue. The glass 
cell so provided should be placed in a horizontal 
position upon the stage, and be filled with water. Dif- 
ferent oils can then be dropped on to the surface of the 
water, and the characteristic cohesion figures due to each 
will be thrown upon the screen. If this latter mode of 
showing the phenomena be chosen, it is obvious that a 
different glass cell must be used for each oil exhibited, 
and I think that it would be quite possible to produce 
lantern slides direct from these oily cohesion figures ; 
although I have not experimented in this direction myself. 
The principle employed would be that of " Lithography." 
The oily figures might be transferred to a piece of glass 
direct from the surface of the water. Those figures could 
be darkened to any extent by employing a greasy printing 
ink, taking care to wet the glass so as to repel the ink ; 
but this is a matter into which,! cannot now afford space 
to enter, and I merely allude to it as a field for profitable 

Many pieces of apparatus have been devised for the 
lantern, which exhibit the principle of what is known as 
kt persistence of vision." In order that we may thoroughly 
understand in what this principle consists, I may men- 
tion that the human eye possesses a peculiar property 
which is highly convenient to its proprietor. What is 
meant by " persistence " is that the retina has the power 



of retaining the image of anything seen for at least one- 
eighth part of a second after the eye ceases to see that 

As an example of this, let me remind my readers, that 
although in the ordinary course of things, we are con- 
tinually "winking," an operation which is necessary to 
lubricate the eyeball, we are quite insensible of the cir- 
cumstance that for the time occupied in doing so, we are 
placed in absolute darkness. Although the eyelids are 
closed and the light is shut out, we have no perception of 
darkness, simply because of this curious property possessed 
by the retina of retaining the image of the object last seen, 
for at least the eighth part of a second. It is for this 
reason, I may also point out in passing, that so-called 
instantaneous photographs of moving objects, such as a 
" trotting horse," &c., appear to us to exhibit such very 
unnatural attitudes. As a matter of fact the photographic 
camera records movements which the human eye, on account 
of this "persistence of vision," cannot appreciate. It is 
evident that if this doctrine be true, the eye cannot appre- 
ciate a movement which takes place in less time than the 
eighth part of a second, and it is because the photographic 
lens can grasp and record the movements which take place 
in a mere fraction of that time, that the attitudes it depicts 
appear to us so highly unnatural. The human eye has 
never seen such attitudes, and never will see them. 

Perhaps the simplest illustration of " persistence of 
vision " is afforded by a burnt stick with a red hot end, 
which is turned rapidly round in front of the observer ; 
<fco that observer the red spot of light looks like a con- 


tinuous ring of fire, but we know well enough that it is 
simply a spark. It is the rapid movement helped by this 
" persistence " of the retina, that causes the spot of light to 
appear to us as a continuous circle. So it is that heavy 
rain drops, which we know very well are independent 
globules of water, appear to be like streaks falling from 
the sky, and like streaks artists invariably depict them. 
And rightly so, too, for we do not wish artists to bring 
before us representations of things as the eye cannot see 
them, but of objects as they appear to us under ordinary 
conditions. For this reason the claim which has been made 
in some quarters, that the unusual attitudes depicted by 
instantaneous photography, should be a help to artists in 
their delineation of animal movement, appears to be ex- 
tremely nonsensical. Such attitudes may certainly be 
studied by artists, as a means of showing how the various 
movements are brought about, just as he would study the 
skeleton of a man, in order to get a better notion of the 
outward form of the body; but both should be kept as 
studies, and certainly not introduced into finished works. 

The kaleidotrope consists of a disc of perforated cardboard. 
It is supported on a spring of wire in such a manner that it 
can be rapidly turned round by the finger as the frame in 
which it is contained stands upon the lantern stage. The 
other end of the spring is cemented to a plate of glass so 
that the light can easily travel through the perforations in 
the disc and be rendered evident on the lantern screen. 
As this card is struck with the finger so as to cause it to 
move and vibrate on its spring in different directions, 
the spots of light on the screen by their movement assume 

N 2 


a great variety of curves. It will be thus seen that this 
instrument simply gives a variation of the burnt-stick 
experiment already alluded to. 

Mr. Beale, of Greenwich, has invented a most ingenious 
and amusing apparatus for the lantern which also depends 
upon " persistence of vision." This is called the choreuto- 
scope, and is made in two different forms. In its more elabo- 
rate shape it consists of a circular plate having upon it figures 
drawn upon glass, and so arranged with their limbs in 
different attitudes, zoetrope fashion, that when one figure 
is rapidly changed for the other, the image seems to be in 
actual movement. The contrivance is so arranged that 
before the figure actually changes a little screen obscures 
it for the moment, so that the movement of the disc is not 
apparent upon the sheet. Mr. Beale has of late years 
simplified this instrument. In this case the figures are 
painted upon a slip of glass about seven inches in length, 
and by means of a special form of slide they are rapidly 
brought in front of the lens in the manner just described. 

The most effective set of figures of any is a skeleton, the 
reason being that it consists only of white on black. 
Such figures can therefore be cut out, stencil fashion, in 
a sheet of thin copper-foil ; the openings in this plate per- 
mitting a far larger amount of light to reach the screen 
than if the figures were drawn upon glass. 

Another far more perfect and elaborate device for illus- 
trating the phenomena connected with persistence of 
vision is an instrument called by the somewhat ponderous 
title, the Astrometeoroscope. The inventor of this clever 
piece of apparatus was the Hungarian mechanician, 


S. Pichler, who designed various other ingenious contriv- 
ances. He was very jealous about this astrometeoroscope, 
and the onlj one made was at the Polytechnic Institution, 
where it was carefully kept under lock and key, except 
when in actual use. When the apparatus of the institution 
came to the hammer, I remember that there was some 
little excitement when the astrometeoroscope was put up 
for sale. Opticians and others would have been glad to 
get hold of it, so as to have multiplied it for sale. This led 
to a brisk competition, ending with Mr. Pichler giving an 
extravagant price for his own bantling. And in that way 
the secret remains in the hands of a few only, and perhaps 
it would be unkind to divulge it. But, at any rate, I 
cannot do much harm by giving a general idea of the out- 
ward appearance of the instrument and its capabilities. 

The astrometeoroscope consists of a narrow box thirteen 
inches in length, and of such a width that at one end it 
will fit the stage of the lantern. At this end it has the 
usual three-inch disc opening, which is occupied by two 
plates of metal which are scored across obliquely with slits 
and which are superposed one. on the other, so that the 
slits on each cross one another diagonally. Now it 
is clear that the only places where light can pierce 
these plates of metal so as to make itself evident on 
the screen is in those places where the slits on the plates 
intersect one another. The effect on the screen, therefore, 
whilst the instrument is quiescent, is a series of dots of 
light all over the screen, but at regular distances from one 
another. By very ingenious mechanism the two plates are 
caused to move to and fro in contrary directions, and the 


speed of either can be varied at will by the operator. The 
effect upon the screen is most curious, for it seems to be 
covered with a lacework of geometrical patterns which 
constantly change their form. 

A very favourite experiment with the lantern, but one 
which it is by no means easy to perform, is the decomposi- 
tion of light by means of a prism. For the most perfect 
effects the electric light is necessary, but as this is beyond 
the reach of most of us, at any rate, for the present, we 
must be content with what can be done with the ordinary 
limelight. The simplest way of showing the spectrum 
with the lantern is to remove the objective and to place in 
the lantern stage a card with a slit in it, as 
shown in the cut (fig. 47). This slit should be 
about an inch in length, and not more than 
one-twentieth of an inch in breadth. The card 
should be placed on the stage of the lantern in a 
IIG. 47. h or i z ontal position and focussed upon the screen 
in front. A prism is then brought into the path of the 
slice of light thus formed, 
and it will be so far bent 
aside as to exhibit the. 
colours of the spectrum on 
the ceiling of the room 
(fig. 48). FIG. 48. 

The prism will require a little turning about before this 
result is arrived at. But at the best this method of show- 
ing the spectrum is but a makeshift one ; it presents, 
however, an easy method of demonstrating the decom- 
position of white light. A preferable mode is to use a 


bisulphide of carbon prism. This takes the form of a 
stoppered bottle with two sides ground away and filled in 
with plates of glass, which are cemented to the re- 
mainder of the bottle. In this way the wedge form 
of the prism is secured. The bottle is then filled with 
bi-sulphide of carbon, and such bottles, ready charged, can 
be obtained at the opticians'. A great objection to them 
is their liability to breakage, for bi-sulphide of carbon, 
beyond being a most inflammable compound, has a most 
disagreeable and pungent odour. 

In using a prism of this description, it is kept upright 
and supported in front of the lantern. The slit in the card 
must in this case be vertical, instead of horizontal, and the 
lantern must be placed at such an angle with the sheet 
that when the spectrum is rendered visible it appears in a 
central place on the sheet. 

There are several means available for showing on the 
lecture-table that the various colours of the spectrum will, 
when combined, once more form white light. Thus we 
may place in the path of the coloured beam a double con- 
vex lens, which will at once bring the scattered rays to a 
focus, and will form a disc of white light. We can also 
recompose light by collecting the coloured rays by means 
of a concave mirror, when a card held in the focus of the 
mirror will exhibit a brilliant spot of light free from 
colour. Another method is to use two prisms placed 
against one another, thus Ay> when one will neutralise 
the effect of the other, and the emergent beam will be 
white. Yet another way of recomposing light is to use a 
number (generally seven) of plain mirrors, which are so 


placed upon a stand that they can each be turned in any 
required direction. The spectrum is allowed to fall upon 
this system of mirrors, and each one is so turned upon its 
axis that the particular colour which it reflects is thrown 
upon one spot. The collective images of the various 
colours then appears as a white disc. 

The methods thus detailed are all good, but cannot 
readily be applied to the lantern. A way of demonstrating 
the recomposition of light with that instrument has 
recently been published in America, by Mr. G. M. Hop- 
kins, and the following remarks are borrowed from him. 
After detailing the various known methods of recomposing 
light, he says : "Besides these methods, the spectrum has 
been recombined by whirling or rocking a prism ; the move- 
ment of the spectrum being so rapid as to be beyond the 
power of the eye to follow, the retina receiving the impres- 
sion merely as a band of white light, the colours being 
united by the superposing of the rapidly succeeding 
impressions, which are retained for an appreciable length 
of time. The engraving shows a device to be used in 
place of the ordinary rocking prism. It is perfectly 
simple, and involves no mechanism. It consists of an 
inexpensive prism, having attached to a knob on either 
end a rubber band. In the present ease the bands are 
attached by making in each a short slit, and insert- 
ing the knobs of the prism in the slit. The rubber 
bands can be held by inserting two fingers in each and 
drawing them taut. The prism can then be held in a 
beam of sunlight, and with one finger the prism is given 
an oscillating motion. The band of light thus elongated 


will have prismatic colours at opposite ends, but the entire 
central portion will be white. To show that the colours of 
the spectrum pass over every portion of the path of the 
light, as indicated by the band, the prism may be rocked 
very slowly. 

"By inserting four screw hooks in a vertical support, and 
stretching the bands over the hooks, the prism is adapted 
for use with a lantern. The light emerging from the 
lantern must pass through a narrow slit to secure a per- 
fect spectrum, and between the screen and the prism 
should be placed another screen with an oblong aper- 
ture, which will allow all of the band of light to appear 
upon the screen, with the exception of the coloured 
extremities. With the prism supported in this way, it is 
an easy matter to turn it slowly back and forth, showing 
on the screen the moving spectrum, which, with the more 
rapid movement, produces the pure white band of light." 

The recomposition of light can be well shown in the 
way just described ; but perhaps a more ready and effec- 
tive, if not quite so scientific, a method is to use a coloured 
disc, fitted as a lantern-slide, with a revolving arrangement 
similar to that used for chromotropes. 

Newton's disc, as it is called, consists of all the colours 
of the spectrum, painted in transparent colours, in their 
right proportions, upon a revolving disc, and as this 
disc is rapidly turned in the lantern, the various 
colours projected upon the screen in front mingle together 
on the retina, and the general effect is that of white 
light. It may happen that a lecturer may touch 
upon the study of spectra without wishing to burden him- 


self with the necessary apparatus for showing them upon 
the screen. Or he may be employing a large lantern to 
illustrate other parts of his lecture, which would be quite 
unsuitable, or, at any rate, would have to be re-arranged 
before a single spectrum experiment could be shown. 
Feeling this want myself, I devised a plan for showing 
spectra diagramatically with an ordinary biunial lantern. 
(It will presently be seen that a double lantern is a neces- 
sity for this particular manner of working), and I have 
found the method adopted to answer admirably. A special 
set of slides is required, but these are not at all difficult 
to make. They must be home-made, for they are not to 
be bought at present, although one well-known optician 
was so pleased with the idea when I described it to him, 
that he expressed his intention of manufacturing slides of 
my pattern. The first of the set is a photographic slide 
showing Newton's well-known experiment with a prism, 
traversed by a beam of light admitted through an aperture 
in the shutter of a darkened room. The next slide is a 
simple-coloured band, or continuous spectrum. This is at 
length replaced by a similar band, no longer continuous, but 
crossed by the principal Frauenhofer lines, which are duly 
marked above with their own distinguishing letters. Such 
a spectrum can be copied from any work on optics, and 
drawn and coloured on ground-glass, as explained in 
another part of this book. We must now prepare a set of 
slides to serve as " effects " for this last spectrum slide, 
and which will consist of simple bright lines. The most 
simple of these would be that due to the metal sodium, 
which would consist of a double yellow line, to agree in 


position with that marked D in the spectrum-slide. To 
produce such a slide it is only necessary to paste over a 
piece of glass a piece of stout black paper, and to cut 
out with a sharp knife, when the paper is dry, the line 
required. A little varnish colour over the cut-out place will 
complete the slide. In using this " effect " the audience 
should have explained to them the theory which seeks to 
explain the reversal of the lines in the spectrum, and at 
the right moment the spectrum-slide is so far darkened 
by moving the lantern-dissolver, that the clear sodium 
line shines out brightly over the spot occupied before by 
the dark D line. I need hardly say that the two slides 
must be in perfect register, or the effect will be spoiled. 
The spectrum-slide can now be once more exhibited, and 
another bright line example placed in the other lantern 
ready to be made visible as the sodium one was just 
now. The spectra of all the different metals can thus be 
illustrated by the bright lines which they afford. The 
method may perhaps be considered rough, but the effect is 
startling, and few among a general audience are able at 
once to realise how it is done. 

Double refraction can be shown on the screen in the 
following manner : A card with a simple perforation about 
one-eighth of an inch in diameter is inserted on the lantern- 
stage, and its image is focussed on the screen. A crystal 
of Iceland spa is then placed between this card and the 
objective lens, and two spots of light will become apparent 
upon the sheet. 

It may be mentioned here that in all experiments where 
colour is required it is better, if possible, to use coloured 


gelatine than any other medium. Ordinary coloured glass 
absorbs so much light that it is of very little use in lantern 
experiments ; and if the operator will try the effect of 
coloured glass and coloured gelatine side by side he will 
be surprised at the advantage gained from using the latter. 
There is one objection to gelatine, and that is, if a very 
powerful limelight be used it is apt to be affected by the 
heat ; but this is only the case if the medium in question 
is kept for a protracted time on the lantern-stage. 

A large number of experiments illustrating the theory 
of colour and the laws of complimentary tints can be 
arranged by means of pieces of cardboard with different 
shaped orifices cut in them, filled in with coloured gelatine. 
Such examples will easily suggest themselves to any 
operator with the assistance of a reliable book on the 
theory of colour. I may mention here a simple arrange- 
ment for showing the way in which the retina becomes 
fatigued by looking at an object for some time. 

It consists of a card with 
two semicircular openings, 
divided by a horizontal bar 
(see fig. 49). Over one open- 
ing, say the lower one, a 
FIG. 49. piece of card is placed so 

that the image of the upper one alone is projected upon 
the screen. After looking at this image for some time, 
the card obscuring the lower opening is suddenly with- 
drawn, and it is then strange to note how one opening 
appears to be far duller than the other, although both are 
in reality equally illuminated. 


Another method which illustrates the tiring of the 
retina, and which also demonstrates the law of compli- 
mentary colours, can be shown thus : 

A card having a round opening in the centre, filled in 
with red gelatine, is placed on the lantern stage, and its 
image allowed to remain upon the sheet for some little 
time, the attention of the spectator being concentrated 
upon it. The gelatine is suddenly removed, when al- 
though the image of the opening is of course perfectly 
Avhite, it appears to be green, because the retina is tired 
by its exposure to the red, and can only for a time appre- 
ciate the remaining colours of the spectrum, which mingled 
form green ; of course, any primary colour can be chosen 
for the experiment, and its complimentary tint will be 
made manifest. This is but a variation of that advertise- 
ment which has been so common in our streets for some 
time, where the onlooker is invited to gaze upon cer- 
tain colours for so many seconds, when the image of the 
coloured letters looked at will appear, but in their com- 
plimentary tint, upon the blank space above. 

For experimental work with the lantern, a special form 
of instrument should be used. I have lately seen a form 
which I think found its origin in Germany ; in which the 
objective is so arranged on a sliding base board, that a 
clear space of some inches is left between it and the lantern 
condensers ; while a little table between the two serves to 
support any object whose shadow it is desirable to throw 
upon the screen. If we are content with the mineral oil 
lantern, and with such a lantern a great many experiments 
can be shown, at any rate in a small room, we can ar- 



range matters in a very simple manner. Let the lantern 
stand on a base board, and let the objective be supported 
upon a sliding piece in front of that board. Cut away the 
tin nozzle upon which the objective fits in the ordinary 
way, so that any object can easily be brought between 
condenser and objective. Or to still more simplify the 
matter, we can use the lamp only of one of these mineral 
lanterns and place it as figured in the annexed cut (fig. 50). 

FIG. 50. 

FIG. 51. 

Here we have a base board A A, with a fixed support in the 
centre B, which is pierced with a hole sufficiently large to 
contain the condensers of the lantern. Close up to this 
is placed the lamp L. Another support, C, holds the objec- 
tive, and this support by means of a sliding piece let into 
the base board, can be moved to and fro for focussing pur- 
poses in front of the condensers. It will be seen that by 
adopting this arrangement, no lantern is necessary. We 
simply require the illuminator, which must of course be 
closed in, as sold with most lanterns ; a condensing lens ; 
and an objective. 

The number of beautiful experiments which are possible 
with the use of a glass tank, or rather, several glass tanks 
of the simple form shown in fig. 51 are surprising. Most 


of these are of a chemical nature, but there are others 
which exhibit physical phenomena in a manner which is 
perhaps, impossible by any other means, or rather, we may 
say, that experiments which can only under normal con- 
ditions be viewed by one or two pairs of eyes on the lecture 
table, can by means of this tank be made visible to a large 

A fine experiment showing the formation of vortex 
rings may be shown in the following way. Having filled 
the tank with clean water, take a penholder or a piece of 
stick pointed for the purpose and dip it into some milk, so 
that a drop forms at the end of it. Bring this carefully over 
the tank and allow the milk to just graze the surface of 
the water, when it will form a white ring in the fluid 
which will fall gradually downward, but on the screen, 
of course, it will appear to rise upward. This ring as it 
travels to the bottom of the tank will give rise to other 
similar rings, so that presently there will be quite a number 
of circles slowly moving upwards on the screen. This 
experiment is one which will illustrate well the formation 
of smoke rings, and of the more important phenomena of 
whirlpools and whirlwinds. 

Another experiment of a similar nature, and giving a fine 
effect on the screen, may be performed by filling the tank 
to within half an inch of the top with methylated spirit. 
Take now instead of a wooden rod one of glass, or a camel 
hair brush will do as; well. Dip it into an alcoholic solution 
of any of the aniline dyes, and just allow the drop which 
hangs from it to touch the inner side of one of the glasses 
of the tank. Directly this drop reaches the alcohol, it will 


descend and immediately break out into a number of 
branches. These branches will on the screen appear to rise 
rapidly upwards after the manner of a number of coloured 
rockets, and by varying the colours of the dyes and putting 
one or two drops into the tank simultaneously, a most lovely 
effect on the screen is obtained. 

The decomposition of water is another experiment which 
has a most curious effect. For this experiment a small electric 
battery is necessary, and the most convenient form to use is 
a single bichromate cell, say of one pint capacity. This can 
be hidden away in a box beneath the lantern, and as it 
gives off no fumes, there is nothing disagreeable in its use ; 
moreover its action, if freshly charged, is energetic, and this 
action can be stopped when required by lifting the zinc 
plate from the solution in which it is immersed. The wires 
from the poles of the battery must be long enough to reach 
the lantern stage ; the slide for this experiment being simple 
in the extreme. The tank to be used shyuld be of rectangular 
form, and as a matter of convenience, it should be furnished 
with two binding screws on one of its outer sides, so that 
the wires from the battery can be readily connected with 
them. These screws should be in connection with two 
gutta-percha covered wires, which proceed to the bottom of 
the tank, where their ends are bare and turned upwards for 
about a quarter of an inch. These ends may be so fixed 
that they are about half an inch apart. The tank is pre- 
viously filled with diluted sulphuric acid (one part of acid 
to eight of water), and is then ready for action. Directly 
connection is made -with the battery, the two wires will 
rapidly give off bubbles of gas, one being hydrogen and 


the other oxygen. It is possible to elaborate this slide by 
crowning the two terminals with tiny inverted test tubes, 
filled with the acidulated liquid. In this case the bubbles 
of gas displace the contained water in the tubes, the hydro- 
gen tube being readily distinguished by being emptied of 
water at double the rate of the tube devoted to the oxygen 
gas. This proves in a very direct manner the composition 
of water, which consists of two volumes of hydrogen to 
one of oxygen. 

In order to show the generation of hydrogen gas alone, a 
still more simple arrangement can be adopted. The electric 
battery is not used for this experiment. A few pieces of 
granulated zinc are dropped into the tank of acid water, 
when bubbles of hydrogen will be rapidly given off, their 
downward descent upon the screen giving a very peculiar 

In like manner carbonic acid gas can be generated by 
using a few pieces of marble instead of the zinc, aud sub- 
stituting for the sulphuric acid water which has been acidu- 
lated with hydrochloric acid. We can also easily show 
that one of the products of the lungs is this same carbonic 
acid gas. In this case the tank must be filled with lime 
water, which will remain perfectly clear until it is blown into 
fro n the lungs by means of a tiny glass tube, when bubbles 
of air will rise from the water, and the liquid will rapidly 
become cloudy, proving that the carbonic acid from the 
lungs has formed carbonate of lime, or common chalk, in 
the water. 

It will be noticed that in all tank experiments it is 
necessary that the lantern stage should be open at the top 


and such experiments are for this reason best performed 
with a lantern having the simple construction shown in 
Fig. 49. These experiments are so valuable for educa- 
tional purposes, and can so easily be shown with ordinary 
oil-lit lanterns that it is to be hoped that manufacturers 
will see the necessity of providing for them by the adop- 
tion of an open stage. 

The composition of Prussian blue can be easily demon- 
strated by means of the chemical tank. For this experiment 
we shall require a solution of the yellow prussiate of 
potash from which the colour takes its name. This is 
placed in the tank. Have in readiness a solution of sul- 
phate of iron or green vitriol. On pouring the contents 
of this bottle by means of a pipette into the tank, a heavy 
blue precipitate is thrown down, but as this precipitate is 
opaque the colour is not perceptible on the screen ; but by 
adding to the blue precipitate a few drops of sulphuric 
acid, and following this by a little bi-chromate of potash 
in solution, a brilliant transparent blue is immediately 
made apparent. The formation of other colours can by 
reference to any book on chemistry be readily demon- 

The tests for acid and alkaline solutions by means of 
litmus can be demonstrated in the following way : 

Fill the tank with a solution of litmus or with an in- 
fusion of purple cabbage, made by slicing a few of the 
leaves, and pouring boiling water upon them. Place either 
of these solutions in the tank, when, upon adding a small 
quantity of acid, the liquid will be seen to turn red ; sub- 
sequent addition of an alkali, such as a weak solution of 


ammonia, will quickly restore the original colour, and these 
changes from red to blue, and vice versa, can be continued 
by adding acid and alkali alternately, as often as may be 

If the tank be charged with a solution of sulphate of 
iron and gallic acid be added to it, a black solution of ink 
will immediately be produced. Another pretty experiment 
demonstrates the presence in hard water of various mineral 
matters which will cause certain chemicals to give a 
precipitate which they would not do in water that has 
been freed from mineral matter by distillation. A good 
plan of showing this is to suspend in a tank a crystal of 
oxalic acid. As the crystal dissolves in the water long 
threads of oxalate of lime will be given off by it, forming 
a very curious appearance on the screen. It may then be 
shown that by the substitution of distilled for hard water 
the crystal will dissolve all the same, but these threads will 
not be given off, because there is no lime present to form 
them. The action of bleaching powder, commonly called 
chloride of lime, is well shown by filling the tank with a 
solution of indigo, which has been acidified with sulphuric 
acid. Upon adding a solution of the bleaching powder, 
the sulphuric acid will liberate the chlorine contained in 
it, and will discharge the blue colour of the indigo, leaving 
the disc on the screen perfectly white. 

The precipitates caused by the admixture of various 
chemicals is not effective in the lantern, for the reason that 
most of these precipitates are opaque, and therefore they 
look black upon the screen. 

For instance, we may fill a tank with a solution of 
o 2 


common salt, i.e., the chloride of sodium, and upon adding 
to this a small quantity of nitrate of silver in solution, a 
heavy white precipitate of chloride of silver is thrown 
down, but as this is perfectly opaque it will only appear on 
the screen as black clouds. 

Other very beautiful experiments may be performed to 
demonstrate the crystallisation of various salts. Plates of 
glass may be prepared beforehand with saturated solutions 
of the salts, and these plates, slipped into a slide carrier, 
can be used for projection, giving very fine effects. But 
by far the most striking way of exhibiting these interesting 
phenomena is to show' the crystallisation actually in 

This is easy enough if the lantern be furnished with a 
vertical attachment, but not so easy without such an 
appendage. But the following experiments can be readily 
performed with an ordinary lantern. Prepare a saturated 
solution of sal-ammoniac, and with the help of a camel-hair 
brush cover a clean glass plate with the liquid ; place this 
glass on the lantern stage, when the heat from the lamp 
will speedily cause the water to evaporate and the crystals 
to form on the glass. It will be noticed that in the crys- 
tallisation of this salt the branches of the marvellous tree, 
which grows so rapidly on the screen, always keep at a 
particular angle to its stem. Another experiment of a like 
nature is performed by employing a solution of urea in 
alcohol, in which the crystallisation is quite different, the 
plate being quickly covered with bundles of fibres which 
are no longer at right angles to the stem from which 
they spring, but take all kinds of different directions. 


These experiments are of great use in demonstrating 1 
the gradual crystallisation of the various mineral sub- 
stances of which the crust of the earth is composed. A 
very beautiful experiment, showing the structure of ice, 
has been devised by Professor Tyndall. I cannot do- 
better than describe the manner of performing it in his 
own words : " Take a slab of lake ice and place it in- the 
path of a concentrated sunbeam. Watch the track of the 
beam through the ice. Part of the beam is stopped; part 
of it goes through ; the former produces internal lique- 
faction, the latter has no effect whatever upon the' ice. 
But the liquefaction is not uniformly diffused. From 
separate spots of the ice little shining points are seen to 
sparkle forth. Every one of those points is sur rounded by 
a beautiful liquid flower with six petals. 

" Ice and water are so optically alike that unless the light 
fall properly upon these flowers, you cannot see them. 
But what is the central spot ? A vacuum. Ice swims on 
water because, bulk for bulk, it is lighter than water ; so 
that when ice is melted it shrinks in size. Can the liquid 
flowers then occupy the whole space of the ice melted ? 
Plainly no. A little empty space is formed with the 
flowers, and this space, or rather its surface, shines in the 
sun with the lustre of burnished silver. 

" In all cases the flowers are formed parallel to the sur- 
face of freezing. They are formed when the sun shines 
upon the ice of every lake ; sometimes in myriads, and so 
small as to require a magnifying glass to see them. They 
are always attainable, but their beauty is often marred by 
internal defects of the ice. Even one portion of the same 


piece of ice may show them exquisitely, while a second 
portion shows them imperfectly. 

" Here we have a reversal of the process of crystallisation. 
The searching solar beam is delicate enough to take the 
molecules down without deranging the order of their archi- 
tecture. Try the experiment for yourself with a pocket- 
lens on a sunny day. You will not find the flowers con- 
fused ; they all lie parallel to the surface of freezing. In 
this exquisite way every bit of the ice over which our 
skaters glide in winter is put together." 

One of the most interesting chemical operations to 
witness is the development of a photograph, and even 
experienced workers will say that they never tire of 
watching the gradual unfolding of the wonderful image. 
Those who have never before had the opportunity of watching 
the effect of the developing fluid on the blank plate, are 
delighted when first the operation is brought under their 
notice. It is certainly an experiment which never fails to 
interest an audience, when properly performed, as it can be, 
in the optical lantern. But the operator mast not be 
a novice in photography, or he will probably fail, for the 
experiment requires experience, land great care in all 
its stages. 

A gelatine bromide plate, such as is ordinarily used 
for negative work,, is of no use whatever here, for the 
film is too opaque for the purpose. A gelatine chloride plate 
(such as that described on page 133) is the right thing to 
employ. If we compare a bromide and a chloride plate side 
by side in the dark room, we shall soon see that there is 
little difficulty in distinguishing the one from the other. In 


the first case, the film is so thick that we can see nothing 
through it, but in the case of the chloride plate the flame of 
the red lamp can easily be seen through the glass ; indeed, 
upon first using such plates, photographers are apt to 
wonder whether so thin a film can ever yield a picture. As 
a matter of fact, the film is as thick as that upon a bromide 
plate, only the emulsion of which it is composed is of a 
far more transparent quality. 

Having then a chloride plate at hand, and having if ne- 
cessary cut it down to a size which will enable it to slip 
with ease into a chemical tank, the course of operations 
will be as follows: 1, Exposure; 2, development; and 
3, fixation. 

Provide a good negative (if it be a portrait of some one 
well known to the spectators, so much the better), and place 
it in a printing frame, with the chloride plate against it, 
film to film. Expose to the light of an inch of magnesium 
wire held two feet away from the printing frame, or to the 
rays of the lime light for about ten seconds. Now place 
the little tank on the stage of the lantern, and against the 
inner side of it, that is, next the light place a sheet 
of ruby glass. The effect upon the screen will now be 
simply that of a blank red disc. The exposed plate may 
now be taken from the printing frame and placed in the 
tank. Take good care that it is placed there upside down, 
so that the image when developed will appear the right way 
up. The developing fluid, ferrous oxalate (see page 121), 
may now be mixed. This should be at hand in two solu- 
tions, so that by mixing the one with the other the de- 
veloper is ready without any delay. As it is poured into 


the tank, the surface of the fluid will appear as a descending 
line across the sheet. The strength of the developer should 
not be so great as for ordinary development, by which I 
mean that the proportion of iron can be conveniently 
reduced so as to render development less sudden than it 
generally is with chloride plates. When once the developer 
has been poured into the tank, the red glass can be with- 
drawn, for the ferrous oxalate developer is red enough in 
itself to form a protection to the plate from the light. 
Presently the image will begin to appear, and will gradually 
gain in strength. When it is fully developed, as it will be 
in about two minutes, the plate can be removed, washed, 
and placed once more in the lantern in a tank of fixing solu- 
tion. Here it will gradually get clear, as the unaltered 
chloride is acted upon by the hyposulphite of soda solution. 

To perform this interesting experiment in the most per- 
fect manner, a special form of tank may be employed. It 
should have a tap at its lower part, to act as a waste pipe. 
With this arrangement the chloride plate need not be 
removed from the tank at any stage of the process. When 
development is complete, the ferrous oxalate can be drawn 
off ; then water can be poured in, to be immediately drawn 
off and replaced by the hypo solution. 

The chloride plate employed can be put into the printing 
frame by gaslight, provided that the operation be performed 
with ordinary despatch. It should be noted, too, that these 
plates, or at least some brands of them, rapidly deteriorate. 
But the careful operator will try the experiment in private 
before he ventures before the public, and will take care that 
his plates are above suspicion. 



Magnetic experiments are always attractive, and can be 
well shown with the lantern, for they gain greatly by the 
magnification possible with that instrument. Fig. 52 shows 
a simple form of slide which can be manufactured without 
much trouble ; it consists of a bar of soft iron, bent as 
shown, and pointed at its ends. These ends or poles are 
brought to within half an inch of each other. Two 
wooden or cardboard reels, wound with a quantity of silk 
covered copper wire, complete the arrangement. The 
battery already recommended can be used with this mag- 
netic slide. Here are a few experiments possible with the 

FIG. 52. 

contrivance. Drop upon the poles some iron filings, and 
show that they are not attracted until the battery connec- 
tion is made, for then and only then has the iron magnetic 
properties conferred upon it. Drop a number of small 
French nails, technically known as pins, upon the poles, 
when they will meet and assume curious forms, until the 
current is broken, when they will fall upward, as it will 
appear. A tiny disc of iron attached to the end of a silk 
thread and hung between the poles will take up a rigid 
position directly the battery connection is made, a similar 


one of bismuth assuming the opposite direction under the 
same conditions. This last experiment is to show the 
difference between a magnetic and dia-magnetic body. 

But the most beautiful magnetic experiments are only 
possible with a vertical attachment fitted to the lantern. 
Obtain a couple of flat bar magnets two inches in length. 
Place one of these in the centre of the horizontal stage, and 
focus sharply on the screen. The appearance is that of a 
thick black bar. Now sift through a muslin bag some iron 
filings, so that the screen appears covered with black spots. 
Tap the stage with the finger nail, so as to disturb the 
particles of iron, and they will be seen to gather round the 
poles of the little magnet, and to form the beautiful magnetic 
curves. A still more striking experiment may be per- 
formed with two magnets so placed that their poles of 
opposite names, N. and S., face one another, while they 
are at the same time about one inch apart. Now scatter 
the filings as before, and the effect of the graceful curves 
embracing one another between the two poles is simply 
magnificent. Remove the magnets, wipe the filings from 
the stage, and once more arrange the bars in the same 
position, but with poles pf the same name facing one 
another. When the filings are now scattered over the 
magnets, a great contrast to the last experiment is apparent. 
Where just now all was harmony, there is visible antago- 
nism. " Poles of opposite name attract one another, and of 
the same name repel one another." And this repulsion is 
most beautifully shown. The curves no longer embrace 
one another, but meet and turn back upon themselves, 
forming a line of confusion where the meeting takes 


place. The experiments can be varied by altering the 
position of the magnets, or by using knitting needles which 
have been just before magnetised at the lecture table. It 
will be noticed that these curve experiments require no 
battery power. They are performed with what are known 
as permanent magnets, in contradistinction to the electro 
magnet used with the special form of slide shown at 
fig. 52. 

In describing some of the experiments possible with the 
optical lantern, I have purposely refrained from detailing 
any of the splendid effects due to polarised light for these 
have been already dealt with by my friend Mr. Lewis 
Wright, in a manner which it would be impossible to 
improve upon. 1 

1 " Light : a Course of Experimental Optics, chiefly with the 
Lantern." Macmillan & Co. 



HEN a photographic aspirant first enters upon the 
practice of what used to be known as the " black 
art," but which now, thanks to the cleanliness of 
dry plate work, no longer merits that stigma, his friends 
and relatives all look anxiously for some tangible results 
from his mysterious operations. To them a negative, 
albeit it may show lovely gradations of tone, and 
beauties of detail, which a master's eye would revel 
in, is negative in a far wider sense than its producer 
would be inclined to allow. A production in which 
bright skies and white skins are black as night, is a 
thing which cannot be understood or tolerated, and until a 
print of that negative is produced, and sometimes alas ! 
even then, the domestic critics are inclined to consider the 
amateur worker a fraud. The painstaking photographer, 
after he has succeeded in obtaining a few negatives, will be 
anxious on this account, if not for his own satisfaction, to 
print some positives from them. These will afterwards be 


mounted in an album, and much pleasure will doubtless be 
derived from them. They may possibly not be grand 
specimens of solar work, but they will serve to remind the 
author of many a pleasant ramble, and many little incidents 
of places visited and people met with, which otherwise 
might have passed into oblivion. He will be able " to fight 
his battles o'er again," as he tells his friends of difficulties 
encountered by the way. But at the best this means a 
great deal of work, and work, too, which to a great extent 
is mechanical, and therefore tedious. The printing, toning 
and fixing of a batch of prints is no light matter to an ama- 
teur, who has generally to do everything for himself. Some 
prints are sure to get over-exposed, others suffer from the 
opposite failing, and even if all goes well in the preliminary 
operation of exposure, there is that terrible toning bath to 
come. This bath sometimes, for some obscure reason, will 
refuse to give the desired colour, and our batch of prints, 
instead of being " joys for ever," turn out to be sandy- 
looking, bilious objects, which we are afraid to show to 

What if some magician were to appear suddenly at the 
elbow of the disgusted worker, and tell him that there was 
a way of producing positives from those negatives without 
all this trouble ? That such positives could be shown en- 
larged to an almost indefinite extent, and that pictures five, 
ten, or fifteen feet in diameter could be shown in perfection, 
the original negative from which they are taken measuring 
only three and a quarter inches. There is no need for any 
magician, for the thing can be achieved, not easily, for the 
work, like most photographic manipulations, requires a 


great deal of patience and practice before success is 
attained. The requisites are good photographic transpa- 
rencies on glass, and a good optical lantern wherewith to 
exhibit them. 

The lantern method of showing photographs has the ob- 
vious advantage that a large number can at the same time 
view the same picture under the best conditions. They can 
exchange opinions as to its merits, and can point out little 
bits of detail which would be almost invisible in a paper 
print from the original small negative. A great many 
amateurs, too, take only small negatives. They do not care 
to be burdened in their rambles with a large camera, 
which, with its inevitable dark slides or changing box, 
forms a very heavy travelling companion. Many, there- 
fore, are wise enough to content themselves with either a 
quarter-plate apparatus, or one which gives pictures mea- 
suring 5 by 4 inches. Prints from these small negatives 
are rather insignificant when mounted in an album, but 
such negatives are just what are required for lantern trans- 
parency making ; so that the tourist with his little camera 
is, with the help of the lantern, placed on the same footing 
as the toiler with large and heavy .apparatus. He can in- 
crease the size of his pictures, or rather the images of such 
pictures, to any reasonable extent. I know of an amateur 
photographer who spent three months on a Mediterranean 
tour. He took with him a quarter-plate camera, and its 
accessories, together with a stock of gelatine plates. He 
brought back with him about one hundred and fifty capital 
negatives, which were taken in Algeria, Tunis, Malta., 
Sicily, and Southern Italy. On his arrival in England 


these were all printed as lantern transparencies, and he is 
now able to entertain his friends with an account of his 
wanderings, and to illustrate his remarks in a very pleasant 
and novel manner. If the same negatives had been merely 
printed on paper in the usual manner, and shown in an 
album, they would, by reason of their smallness, have met 
with but scant appreciation. 

I may instance another way in which the lantern can be 
utilised without the necessity of taking original negatives. 
Most travellers abroad collect photographs of any place they 
may visit, and an enormous trade is now done in such 
pictures. These are brought home in due course, mounted 
in an album, and too often, alas ! gradually fade into sickly 
yellow ghosts of their former selves. Now, if these pictures 
were copied by a small quarter-plate camera, the negatives 
thus obtained could in their turn furnish positives on glass 
for use in the lantern. Transparencies so produced are 
never, it is true, so good as those from original negatives, 
for the texture and the gloss of the paper prints will gene- 
rally to some extent show themselves in the reproduced 
negative, but still it is wonderful what good results can be 
obtained in this way. Indeed, I may say that it requires a 
critical eye to detect that a second negative has been em- 
ployed. I have already detailed the best method of pro- 
ducing these negatives from paper prints, and have given 
some useful hints by which the disadvantages to which they 
are subject can be reduced to a minimum (see page 121). 

Paper prints naturally remind one of those portrait 
albums which are found in every house. Why should not 
these pictures also be adapted to the lantern? What a 


fund of interest and amusement could be obtained from 
an exhibition of life-sized pictures of friends and acquaint- 
ances well known to the family circle ! There is really 
no great difficulty in obtaining such pictures when the first 
principles are understood; and when practice has given 
experience, negatives from prints can be produced with a 
rapidity and certainty to which the most experienced land- 
scape photographer is a stranger. 

Nor must the young folks be forgotten. Although the 
" man swallowing rats " and the other monstrosities, known 
in the trade as " comic slips," still have an attraction to the 
eye of youth, surely we can manage by the means now 
easily within reach, to place before the youngsters some- 
thing better worth looking at. The quaintly picturesque 
little youths and damsels drawn by Kate Greenaway would 
have additional charm for their living playfellows if shown 
life-sized on a screen ; and nursery legends, as interpreted 
by Cal&ecott's clever pencil, would acquire a new interest if 
shown in the same fashion. Perhaps as amateur photo- 
graphy increases its number of workers, as it is rapidly 
doing, artists may find it convenient to draw subjects 
specially for reproduction as lantern transparencies. 

There is one feature in this particular class of photo- 
graphic work which I have not yet dwelt upon, and that 
is, the possibility of producing these transparencies inde- 
pendently of daylight. So long as the spring, summer, and 
autumn days are upon us, the possessor of a camera finds 
much other work to employ his time. His labours are 
mostly in the open field, adding to his stock of negatives, 
and he looks forward with regret to the many dark hours 


which winter must bring, in which such work is impossible. 
But now is his time for lantern preparation. The negatives 
are looked up and sorted out, and by means of a gas flame 
or paraffin lamp he can print off transparencies more 
quickly than even on a favourable day he could produce 
paper prints. There is no tedious toning or extended 
washing necessary, and therefore the work does not entail 
half the trouble that he is accustomed to in ordinary print- 
ing. In addition to these advantages there is one other. 
A transparency on glass is far finer in effect than any 
paper print, for the reason that the picture is absolutely 
without texture. Magnify a paper print and the texture 
of the paper becomes at once evident; treat a good 
glass positive in the same way and its beauty is only 

Lastly, the possessor of a lantern has another field of 
work in which it can be usefully and efficiently employed, 
namely, in making enlargements. Not the evanescent 
and fleeting images already described, but permanent en- 
largements of a quarter-plate negative, which is sufficiently 
rich in detail and interest - to warrant its production in an 
enlarged form. By means of an oil lantern, and a sheet 
of the excellent gelatino-bromide paper now to be pur- 
chased, an enlarged positive from a small negative is easy 
to produce. And here, again, the work is quite indepen- 
dent of the fickle sun, and can be accomplished in any 
room not specially set apart for the purpose. 

I have by no means exhausted the list of services 
which a simple form of optical lantern is able to render, 
but I have enumerated several which will serve my pur- 




pose in pointing out its extreme utility. In a subsequent 
chapter on enlarging I dwell in detail upon the various 
operations necessary, and illustrate them by diagrams, 
so that readers may acquire a practical knowledge of the 
necessary manipulations. 



PHOTO-MICROGRAPH is the picture of a 
microscopic preparation, as seen by the eye 
when enlarged by means of the microscope ; 
its converse, being a much-reduced image of an object 
photographed on glass, which is called a micro-photograph, 
and which can only be seen when placed in the microscope. 
This latter, however, is a mere curiosity, and, although 
it excites some wonder when looked at, has no educational 
or scientific value, except perhaps as a proof of the fine 
structure of a photographic film. A photo-micrograph, on 
the other hand, affords a valuable means of displaying to a 
large audience the delicate structure of various organisms, 
both animal and vegetable ; besides which that of coal and 
other minerals can: be well exhibited. Lantern micro- 
scopes, some of very beautiful construction, have been 
brought forward from time to time, and one of them, at 
least, I shall refer to in a subsequent chapter. 

But although lantern microscopes may give very fine 
results, it is an indisputable fact that the amount of light 
which is able to get through the tiny aperture of a high- 
power objective, is small. And when this small amount 

p 2 


has to be spread over a screen of even moderate propor- 
tions, the illumination of the whole is so insufficient that 
although near observers are able to note that the disc is 
covered with a network of exquisite detail, those who are 
placed a few yards away cannot distinguish anything of the 
kind. If this is the case with those whose sight is perfect, 
how much more true it must be of the large number of 
persons who are less favourably endowed. Probably the 
difficulty may be remedied at an early date by the use of 
the electric light, which is far more brilliant than the best 
limelight possible, and I know that experiments are 
being carried on in this direction ! In the meantime, we 
must look for other means of projecting the image of 
microscopic objects on a screen if we require such illus- 
trations for a large number of spectators. I recommend 
the employment of photo-micrographs of the size of the 
ordinary lantern-slide, viz., 3J x 3J in. as the best way out 
of the difficulty. I am, of course, aware that a photo- 
graph of an object is not in many cases so good as the 
object itself. While this is true, it is also true that there 
are a great many preparations which cannot be satisfactorily 
shown by any kind of projecting apparatus, but they can 
be made to yield photographs which can be exhibited by 
the optical lantern. There are many different ways 
of producing photo-micrographs. Some workers use the 
most complicated apparatus, whilst others seem to obtain as 
good results with rough home-made appliances. But so it 
is in every branch of science. Somebody wittily divided 
microscopic workers into two different species. He dubbed 
the first of these " Brass and Glass," and the second 
" Bug and Slug." The first are the possessors of the 


magnificent microscopes with all kinds of movements and 
expensive attachments, and who toy with their instruments 
rather than work with them. The second class are the 
hard workers, who will be content so long as they possess 
one or two good powers, and have anything in the shape 
of a stand to hold them in position. They will accomplish 
far more real work with a simple magnif ying-glass than one 
of the "Brass and Glass" fraternity with his gorgeous 
array of instruments. 

One of the most simple methods of obtaining a photo- 
graph from a microscopic object is to use a little camera, a 
cardboard box with a hole at the bottom to fit over the 
microscope tube is sufficient, placed above the microscope 
as it stands upright on a table. To simplify matters, the 
eyepiece' of the microscope should be removed, a method of 
procedure which I recommend in all cases. The upper part 
of the cardboard box should be furnished with a lid on a 
hinge, and should have a curtain of black velvet all round it, 
to prevent any access of light. On its inner sides, half an inch 
below the lid opening, should be glued four little pieces of 
wood to support the focussing screen \ the same support 
serving later on to hold the sensitive gelatine -plate in posi- 
tion. Now let us go through the required operations. The 
image is focussed by daylight, or lamplight, as the case 
may be. The focussing glass is then removed, and while 
the room is darkened the sensitive plate is inserted in its 
place, the lid of the box shut down, and all is ready for ex- 
posure. The time of exposure is of course a matter depend- 
ing upon a host of circumstances to which we need not here 
refer. The exposure having been made, the plate is de- 
veloped in the usual manner. 


Another plan is to bring down the microscope to the 
horizontal position, and most microscopes allow of this 
being done, and to push the end of its tube into the flange 
opening of an ordinary photographic camera, with the lens 
of the latter removed. But both these methods have 
a disadvantage, among many other drawbacks, which 
will at once disappoint the operator. The image afforded is 
so small. The tube of the microscope gets in the way, so 
to speak, and a large portion of that image is cut off. This 
can be remedied by an arrangement of the apparatus which 
I am now about to describe, and by which I have taken a 
number of photographs which leave little to be desired in 
point of excellence, while the necessary manipulations are 
carried forward with that ease and nicety which go far to- 
wards the production of first-class results. 

Let it be at once pointed out, in spite of the opinions of 
our " Brass and Glass " friends, that an expensive instru- 
ment is not required for this work. (Indeed, I will presently 
point out how it is possible to obtain capital photo-micro- 
graphs without any microscope at all, although the essen- 
tial part of that instrument, the objective, must be 
employed.) What is wanted is a good firm stand, and a 
fine adjustment, and even this is not very necessary, unless 
high powers are employed. But the majority of readers 
will look for some ready means of photographing objects of a 
popular character. The proboscis of a blowfly, the industrious 
flea (or bee is it ?), section of the echinus spine, and so on ; 
such things as can be readily photographed with the " inch" 
objective. And to readers who are content with such as 
these I chiefly direct my remarks, leaving them to study 
the excellent treatises and articles upon the subject of 



photo-micrography, which have been published, when they 
feel themselves capable of 
higher flights in this most 
interesting domain 
scientific research. 

The microscope which 
I use is of a very ordinary 
pattern, as may be noticed 
in the diagram (fig. 53) ; 
but three little alterations 
in it make it very con- 
venient for photographic 
work. In the front leg 
of the claw-shaped stand 
a 3-16ths inch hole has 
been bored, so that the 
instrument can by means 
of a screw be rigidly 
fixed upon a base board. 
The next alteration is in 
the length of the tube. 
Originally seven inches 
long, I have had it 
separated at nearly the 
centre, so that it can be 
reduced to three inches ; 
but an inner tube over 
which the outer one 
tightly fits, allows me to 
use the microscope for ordinary purposes with a tube of 


normal length. The third modification which I have intro- 
duced, is a groove cut in the milled head of the fine adjust- 
ment screw, the purpose of which we shall presently see. 
For photographic work, the mirror is thrown out of gear, 
as indicated in the diagram, for it is not required. 

Referring once more to this diagram, 1 1 is the table on 
which the whole arrangement rests, and it is best to have 
a table for the purpose, or at any rate a level base board? 
upon which all necessary fixtures can be made; c is a 
camera which should open out to great extent (most 
modern cameras are made to do so, so as to give the 
photographer the benefit of using long-focus lenses) ; 
m is the microscope, s the stage, p the mirror thrown 
back out of use, n the coarse adjustment, and k the fine 
adjustment. We can now see the advantage of providing 
this milled head of the fine adjustment screw with a 
groove. In this groove is placed a silk cord, which 
works in a corresponding groove in the little wheel 
which is fixed on the end of the focussing rod o o. By 
means of the knob d at the other end of this rod, the 
operator is able to work the fine adjustment to a nicety, 
while he is far away from the microscope, examining 
the image on the ground-glass screen of the camera. 

A word about this screen will not be amiss. Ordinary 
ground-g'ass will not do for this class of work, for it is 
far too coarse. It should therefore be replaced by a 
focussing screen prepared as follows : Obtain a sensitive 
gelatine plate, such as is used for negative work, expose 
it to the light of a gas flame for a second, and then pro- 
ceed to develop it. Develop until it is uniformly 


darkened to a small extent, fix and wash in the usual 
manner, and then bleach it in a solution of mercuric 
chloride. The result will be a plate covered with an 
exquisitely fine translucent surface, upon which the 
finest details will be visible. The exact amount of 
exposure and development to secure this end may not 
be at first hit upon, but one or two trials will be sure to 
end in a satisfactory result. Some workers prefer to use 
a plain glass upon which fine lines have been ruled 
with a writing diamond. In any case the worker will 
find the advantage of supplementing his eyesight, how- 
ever good, by a focussing glass. In this way a far sharper 
focus is obtainable than by the unaided eye. 

To describe the rest of the diagram, let me point out 
that / is an ordinary microscopic paraffin lamp, furnished 
with a reflector f, and that h is a condensing lens, having 
attached to it a diaphragm-plate, e. 

Mr. T. Charters White, M.R.C.S., has published a 
method by which photo -micrographs can be produced 
without the aid of either a camera or a microscope, which 
is very creditable to his ingenuity. I had recently the 
pleasure of hearing him 'describe the instrument, while 
he practically demonstrated how effectually it would 
work. The apparatus was home-made, and such as 
could be produced by any one with the minimum of out- 
side help, although there are many accustomed to the use 
of tools who could easily make it without any help at all. 
I append a diagram which shows the various parts of this 
simple contrivance (see fig. 54). 

It consists in a lidless box sufficiently large to con- 



tain an ordinary microscopic lamp, an objective whicli 
screws into one end of the box, and a movable stage 

FIG. 54. 

to hold the object, having a screw attachment, so that 
it can be moved to and from the objective in order 
that the image may be sharply focnssed upon a plate 
held in a frame outside. This frame is fixed to a 
grooved board, which can be moved in and out of the base 
board, and this movement determines the distance of the 
image projected from the lens, and therefore the size of 
that image. The apparatus may indeed be compared to 
an optical lantern in its arrangements, except that the 
condensing lens (an ordinary one on a stand such as is 
used for microscopic work) is contained within the box, 
and that the object to be projected is on a special form of 
movable stage, as above mentioned. This stage, or fine 
adjustment, consists of two parallel and horizontal bars, 
with a fine screw of the same length laid between them, 
and which works in a threaded orifice in the lower part of 
the stage. The end of this screw nearest the light is 


crowned with a grooved wheel, which is geared by a piece 
of cord to another similar wheel at the end of a focussing- 
rod, which is brought within easy reach of the plate- 
carrier outside the box. 

These various arrangements will be rendered clearer by 
reference to the diagram, where O is the objective, S the 
stage, F the focussing-rod, L the lamp, C the condenser, 
and A the frame holding the gelatine plate, or the 
focussing -glass, as the case may be, for one takes the 
place of the other. And let me say, in passing, that this 
method of withdrawing one glass so that the other can 
take its exact place, is the best that could be adopted, for 
the merest fraction of difference in register would be 
perceptible in photo-micrographic work, while it might 
remain undiscovered in negative taking of the ordinary 

Mr. White's apparatus was, at the time I saw it, fitted 
with a 1-inch objective; but he told me that he had 
used higher powers with it. It certainly is capable of 
very fine work, as was proved by an album full of speci- 
mens which he exhibited. His focussing-screen was a 
plain glass, ruled with -lines by a diamond, and he 
employed a focussing eye-piece. But it is evident that, 
with this method of working, the operator could employ 
an opaque screen, such as a piece of opal glass, for the 
room in which the work is carried on takes the place of 
the camera, and he is practically within it, and can 
look upon the side of the screen which is next the 
light. By means of a scale upon the sliding-board which 
carries the gelatine plate, it is easy to note, without actual 



measurement, the amount of magnification of the image. 
And this magnification can be carried to any reasonable 
extent, for the worker is not limited, as he would be if 
using a camera, by the length to which that camera can 
be extended. 

But perhaps the simplest arrangement of all is that 
recently introduced by Messrs. Mawson & Swan, and 
which is shown at fig. 55. A is a light metal disc, which 

Fig. 55. 

can be screwed on the camera front in place of the ordinary 
lens. The opening in -its centre is furnished with the 
regulation microscopic screw, so that any ordinary micro- 
scopic objective can be readily fixed to it. Upon two 
horizontal bars, projecting from this metal disc, there 
slides another similar disc B, also with an opening in the 
centre. This second disc has fitted to it a pair of small 
spring clips for the reception of the microscopic slide 
which it is desired to photograph. Focussing is effected 
by sliding the disc B to and fro in front of the objective 


on A. It will be readily seen that the apparatus may be 
rendered more effective by the attachment of a screw, or 
fine adjustment for more accurate focussing ; but with the 
lower powers this would not be needed. It is an addition, 
however, which the makers will supply when required. 

All the objectives made by Messrs. Swift, as well 
as those by a few other makers, are corrected for 
photography, but in those of older date the visual focus 
does not agree with the chemical focus. As a rule, no 
difficulty will be found with the higher powers, and with 
the others a few trials will soon show what allowance in 
focussing must be made. As a rough guide to what must 
be done to correct this fault, which is rendered evident 
by a sharply -focussed image appearing blurred in the 
negative, proceed as follows : First focus the image as 
sharply as possible, and then cause the objective to 
approach the object until the latter seems to be sur- 
rounded by a reddish light; now take the photograph, 
and it will be sharply defined, although the image did not 
look so on the focussing screen. 

The ferrous-oxalate method of development, described on 
a former page, is very suitable for negatives taken for 
photo-rnicrographs. These negatives are then made to 
furnish lantern slides in the manner detailed in a former 



(HE amateur who works with a quarter plate 
camera will often congratulate himself upon 
the slight burden which it entails, even when 
several double backs and spare plates accompany 
it. But he will also regret that the little pictures 
which it yields, measuring only 3 by 4 inches when 
trimmed and finished, are, after all his trouble, so 
very insignificant-looking. He may possibly have availed 
himself of the instructions already given for the produc- 
tion of lantern slides from such small negatives, and thus 
ascertained that his pictures are full of detail, and will 
bear enlargement. But lantern images are fleeting things, 
dissolving views, in truth, and he would fain endeavour 
to find some more permanent way of increasing the size 
of his pictures. Thanks to the wonderful photographic 
revolution achieved by gelatine emulsion, this can be done 
without very much trouble or difficulty. 

In using the lantern for exhibition purposes we employ 


for slides transparent positives on glass, and it stands to 
reason that, if the sheet or surface upon which the image 
is thrown were, by chemical means, to be made sensitive 
to light, we should obtain much the same result that we 
get by means of our camera, a negative image, which can 
be rendered visible by development. If, on the other hand, 
we employ one of our little negatives as a lantern slide, 
we can produce from it a positive. Such is the theory 
which we will now endeavour to reduce to practice. 

The lantern employed can be of the ordinary kind used 
for projection, but in this case, where the condenser only 
measures 4 inches, it is obvious that a negative measuring 
less than that size will be the only one available. The 
operator will therefore be better off with a lantern made 
specially for enlarging purposes, the condenser of which 
must be at least 5 inches in diameter to accommodate a 
quarter-plate negative. It might, in many cases, be prac- 
ticable to fit the ordinary lantern with a condenser of that 
size when it is proposed to use it for enlarging purposes. 
Whatever be the arrangement, there must be in front of 
the lens of the lantern a flat board upon which the image 
can be projected, and which .will serve as a support for the 
sensitive surface at a later stage of the operations. 

A convenient form of upright easel is shown at fig. 56. It 
can be moved backwards and forwards between a couple of 
laths nailed on the floor, while the enlarging lantern 
remains stationary. A light-tight box above it contains a 
roll of sensitive paper, which can be pulled down and cut 
off in lengths as required. This easel has a hinged frame, 
so that when a sufficient length of the paper is drawn down 


over the face of the easel, which serves as a focussing 
board, the frame shuts it in and is clamped. In this way 

FIG. 56. 

the paper is heM tight without the necessity of using pins, 
or other loose fastenings. 

Fig. 57 shows a larger view of this box, with its supply 
of sensitive material. But the beginner would no doubt, 
first of all, experiment with a simple board, and one 
measuring 12 inches by 10 inches would be ample. 

The sensitive surface to be employed when a direct 
positive is required, is paper specially prepared with a 


coating of gelatino-bromide of silver emulsion. If an 
enlarged negative is desired, either an ordinary gelatine 
(glass) plate of the required size may be employed, or a 
paper negative can be made in the manner to be presently 
described. Messrs. Morgan & Kidd, of Richmond, were 

FIG. 57. 

the first to introduce " argentic gelatino-bromide paper," 
and therefore the circumstance should be noted to their 
credit. It can now be obtained from most other dealers, 
and its manufacture is so well understood that it will be 
found generally reliable. It can, of course, be used for 
contact printing as well as for enlarging purposes. But 
perhaps the sanguine amateur may prefer to manufacture 
it for himself, and there is no reason why he should not 
succeed in doing so, if he is already master of the secret of 
making an emulsion which neither fogs nor frills. Here 
is a necessarily brief outline of the method of going 
to work : 

Procure some good plain Saxe paper. Having made 
and filtered your emulsion, allow it to set to a jelly in a 



dish. With a good stiff hog-hair stencil-brush break up 
the cold jelly, and rub it vigorously over the paper, just as 
you would break up cold starch jelly in mounting prints. 
Now drag the paper slowly over an earthenware foot- 
warmer, which has been duly charged with boiling water. 
The heat will cause the little specks of jelly on the paper 
to melt and mingle, and the whole will present a smooth 
surface. The paper must now be hung up to dry, or it 
may be used at once. I need hardly say that all these 
operations must be conducted by non-actinic light. The 
majority of workers, however, will prefer to buy their 
argentic paper ready-made, and, by doing so, save them- 
selves possibly much vexatious disappointment. 

Any room will serve for the purpose of making an 
enlargement ; but it is preferable to conduct the work 
at night, because then is saved the trouble of darkening 
a room so that it is really fit for photographic opera- 
tions, by no means an easy matter. Having a dark 
room, the further requirements are a lantern, a screen 
as aforesaid in front of it, with a sheet of white paper 
pasted over its surface, a good red lamp, a developing 
dish, the necessary chemicals, and, lastly, plenty of water 
and a pail for waste solutions. If the room has in 
it a tap and sink, so much the better. The negative 
(which should be a good one, or it will not be worth 
enlarging) is placed in the lantern like an ordinary slide, 
taking care that the film side is turned towards the screen, 
and away from the light. Now carefully focus its image 
011 the white board. Having placed lantern and screen at 
such a distance from one another that the image is of the 


required dimensions, and having seen that that image is 
as sharply focussed as possible, it will be as well if a slip 
of sensitive paper, say, 1 inch wide, is first of all exposed 
as a pilot. 

In the hurry and bustle incidental to, if not inseparable 
from, every -day life, we all have a tendency to work too 
much by rule of thumb, and it must be confessed that rule 
of thumb often turns out very good results. But, in spite 
of this, and of the old adage to the effect that an ounce of 
practice is worth a pound of theory, we cannot afford to 
give theory the go-by entirely. Theory is a useful servant, 
but a bad master, for those patient, plodding creatures who 
think of nothing else seldom turn out work which has the 
stamp of genius upon it. Theory holds them down in her 
rigid grasp, and they have not the pluck to try anything 
or dare anything that seems opposed to her teachings. If, 
on the other hand, theory be regarded as a reliable servant, 
to be consulted when difficulties occur in practice, her 
value will soon be recognised. 

These thoughts came into my mind once when watching 
a young experimenter, who was endeavouring to make 
some enlargements on bromide paper from small negatives, 
by means of an oil lantern. The negative was placed 
on the stage of the lantern, and its image was projected 
upon the side of a wooden packing-case, which stood on 
the table in front of it. My young friend was endeavour- 
ing to make from his small negative (J-plate) enlarged 
copies of different sizes ; and, to obtain the different sized 
images, he had, of course, to move the focussing surface 
either to or from the lens as the image was required to 
Q 2 


be smaller or larger. But with regard to exposure he 
worked entirely by rule of thumb, or rather, I might 
sa y> by no rule at all. It was all guesswork, and, 
although he tried many pilot slips of paper with watch in 
hand, he failed to turn out any really correctly-exposed 
pictures. His failure was chiefly due to his utter ignorance 
of the law in optics, which has been already considered 
on page 118. 

Referring once more to fig. 39 on that page, let the four 
squares numbered 1, 2, 3, and 4, be printing-frames 
placed at distances of 1, 2, 3, and 4 feet from a 
candle-flame. Let us suppose, also, that we have ascer- 
tained by experiment that the plate or paper in the first 
position (No. 1) is sufficiently affected by the light if it 
remain there for one minute. (This is, of course, merely 
stated as a case in point. Bromide paper at such a distance 
would be sufficiently exposed, under a normal negative, in 
about eight seconds, while a chloride plate under such con- 
ditions would want two minutes or more.) Then, if we re- 
move the frame to position No. 2 at 2 feet from the light 
source the necessary exposure will not be doubled, as some 
might think, but quadrupled. For the square of 2 is that 
number multiplied by itself, i.e., 4. The right exposure, 
therefore, will be four minutes. Removing the frame to 
position 3, we must once more square that number in 
order to arrive at the right number of minutes, for ex- 
posure at this increased distance. 3 x 3 = 9. Therefore 
nine minutes will be the time. It is easy to see that when 
the printing-frame is removed to the farthest distance of 
all, which is 4 feet from the light source, the exposure 


will be sixteen minutes. To make the diagram more 
explicit, the vertical squares 1, 2, 3, and 4, have been so 
subdivided that the number of spaces in each indicates 
the number of units of exposure, be that unit a second, a 
minute, or an hour. The same rule holds good for en- 
larging operations. Thus, supposing that we are working 
with an optical lantern, and that the necessary exposure 
at 1 foot from the lens is half a minute ; at 2 feet the 
time will be two minutes ; at 3 feet four minutes and 
a half ; and so on. The practical worker will have this 
little bit of theory in his mind whenever he is operating, 
and he will soon be convinced that the theory is strictly 

Another help in enlarging, which will be found useful, 
is a little piece of apparatus, if it can be dignified 
by that name, which I have lately made, and which I 
call an exposing-gauge. It is so simple in construction 
that any one can make it out of a couple of strips of card- 
board. The arrangement is shown in fig. 57. The size 
of the gauge is immaterial, but a length of 20 inches 
will be found convenient. A slip of card of that length, 
and about 1 inch in breadth, is cut with pointed ends, 
each point having a hole pricked in it as shown. By these 
holes, and with the assistance of a couple of drawing-pins, 
the contrivance can be readily attached to any flat surface 
upon which the enlarged image from the lantern is 
focussed. Placed above this slip is another piece of card 
slightly shorter, and with a round hole in the centre. The 
two strips are bound together with pieces of tape glued 
over their upper and lower edges, the two ends being left 


open, like a sleeve, for the reception of a slip of paper, 
like that shown in fig. 58. 

FIG. 58. 

I I- '.I ' I -M l 

FIG. 59. 

Fig. 59, as indicated, really consists of two slips of paper 
gummed together end to end. One is sensitive bromide 
paper, ten inches in length, which has been spaced out 
into five divisions, and marked , b, c, d, e, with an aniline 
ink pencil. The other part is ordinary white cartridge 
paper, slightly longer than the sensitive slip. Its purpose 
is to serve as a handle by which to pull the sensitive paper 
through the sleeve, and also to furnish a white surface 
upon which a small part of the picture can be focussed, 
that small part being confined to the central circular hole 
in the upper card. 

Now let us see how the gauge is used in practice. It is 
first pinned on the focussing board so that a distinctive 
part of the image is thrown upon the central hole. In the 
case of a portrait this should be the eye. Having focussed 
carefully on the blank paper, the first division of the 
sensitive slip, which will be that marked e, is pulled in 
front of the opening. Let this be exposed for, say, fifteen 
seconds; then pull the slip onwards, and expose d for 
twenty seconds, c for twenty-five seconds, and so on. The 
gauge is then taken into the dark room, its slip of sensitive 
paper taken from its yoke-fellow, and carefully developed. 


It will then soon be seen which of the lettered spaces has 
received the correct exposure ; and a memorandum noting 
time and distance of lens from screen can either be 
attached to the negative, or entered in a book against a 
number corresponding with a number scratched on the 
glass negative. 

The same principle can be applied to contact printing 
in a frame on bromide paper, by gas or lamp light. When 
the frame has been charged with its negative and the 
bromide paper, support it upright at a distance of, say, 
18 inches from the turned-down flame. Now, place 
in front of it an opaque card, sufficiently large to more 
than cover the frame. This card should have a hole about 
1 inch in diameter cut in it in one corner. Turn up the 
light and expose for five seconds. Alter the position of the 
hole and give ten seconds, and so on. When the paper is 
subsequently developed the several exposures can be 
readily identified, and the negative can be labelled to the 
effect that it requires so much exposure at a given distance 
from a flame. Thus Bromide paper, 18 in. 25 sec. This 
negative will then be an infallible guide for the exposure 
of negatives of a similar 'type; for a systematic worker, 
unless he be quite a beginner, will fall into the way of 
producing negatives of much the same character and 
strength, and printing from them by lamp light will then 
become an easy matter to him. 

After this somewhat long but not unnecessary digression, 
I will resume my directions for enlarging on bromide 
paper, and for the sake of simplicity will suppose that the 
operator is not supplied with the special form of easel 


which I have referred to, but is using a mere board for the 

The paper is supplied in cases, either in flat sheets, or 
rolled with the sensitive surface inwards. A piece of the 
required size is pinned on the focussing board ; and the 
best way to do this is to pin the two upper corners 
first, and to unfold the paper over the board, pinning it 
down at the edges as required. Drawing-pins will do, but 
ladies' bonnet pins are much more easily handled in the 
semi-darkness of the room. Now uncover the lens for the 
proper time, and be careful that the lantern is quite free 
from vibration. If you wish the picture to be vignetted, 
this is most easily managed during exposure. A piece of 
brown paper, a foot square, is cut in the centre with an 
oval opening, with a serrated edge. Hold this in front of 
the lens, and keep it in gentle movement, so that the 
pointed edges of the paper are always changing their places. 
This will cause the edges of the picture to be ill-defined, 
and a white margin will be left outside them. 

I need hardly point out that in enlarging by this method 
the operator has a wonderful amount of controlling power 
at his disposal, in bringing out certain parts of the picture 
with extra density, and reducing those parts which may 
require such treatment. Thus the distant portion of a 
landscape may be lightened by a card moved with discre- 
tion over that part of the image during exposure. If, too, 
some point in the negative is of unusual density, it can 
receive extra exposure by using a card with a hole in it, 
in front of the easel. 

At the end of the exposure the lantern is capped, the 


paper is unpinned, and carried to the developing dish. It 
is now saturated with cold water on both sides, and clean 
hands may assist in spreading the water over the surface 
until it lies perfectly flat on the bottom of the tray. The 
water is now drained off and the developer applied. The 
ferrous oxalate method is by far the best to adopt, but the 
proportion of iron should be reduced to about one-sixth, or 
even one-eighth of the oxalate solution ; and to insure the 
best results, the exposure should be such that only a very 
small dose of bromide solution is necessary. Some workers 
prefer to bring the image out slowly by using an old 
ferrous oxalate solution. I myself prefer it mixed per- 
fectly fresh, and am quite certain that if the best results 
are looked for, fresh developer should be mixed for every 
print required. The development must not be carried too 
far, for the image gains in density under fixation. When 
development is judged to be complete, drain off the liquid, 
and immediately, without washing, flood the surface of the 
picture with an acid solution. 

Acetic acid (glacial) ... ... 1 drachm. 

Water ... ... ... ... 16 ounces. 

The addition of this solution keeps the whites of the pic- 
ture pure. In a minute or two pour the acid away, wash 
the print, and fix in fresh hypo of the usual strength. The 
print ought to be fixed in about ten minutes ; if it is allowed 
to remain in the hypo longer than necessary the half-tones 
are quickly destroyed. Now wash the paper in several 
changes of water, and let it soak for a couple of hours at 
least before drying. 

It is not very difficult to print in clouds, from a separate 


negative, on an enlarged positive on bromide paper. The 
process depends upon the circumstance that the paper 
remains sensitive to light, but in a diminished degree, 
after the developing solution has been applied to it. Pro- 
ceed as follows : Expose your landscape as usual, but stop 
development before the required density is obtained, and 
wash the paper. Now placing your cloud negative in the 
lantern, pin up the paper once more, shielding the land- 
scape portion by a piece of card kept in movement, and 
give another exposure. Now re-develope to the right 
density, and you will find that while the landscape gains 
in strength the clouds will become faintly apparent. The 
picture can then be fixed and finished according to the 
directions given. 

If several copies of an enlargement are required, the 
best method will be to make an enlarged negative on 
paper, using a glass positive (an ordinary lantern slide) in 
the lantern. The same operations as those just described 
are necessary, but the exposure can with advantage be 
increased. I should also recommend the use of alkaline 
development, and I think that washing soda and pyro is 
the best form of it for the purpose. The paper negative 
when dry is rendered transparent by being passed through 
a bath of melted paraffin wax. It can then be used in 
an ordinary ' printing- frame to produce prints as may be 

Some time ago I published a new method of obtaining 
enlarged negatives, which will' be useful to those who wish 
to work with an ordinary lantern, and who are ready to 
undertake the task of plate-making. 


1 had occasion to obtain from some half-plate negativss 
some copies of them on plates measuring 16 by 13. The 
problem I put to myself was this, which is the quickest 
and best way of accomplishing the work ? After some 
consideration I determined to work with the limelight, 
for the weather was dull and uncertain at the time I am 
speaking of, and 1 thought that I would at once eliminate 
one common source of error by adopting a mode of illumi- 
nation which represents a constant quantity. This being 
settled, I next thought over the different systems of en- 
larging, and finally decided to try a new plan. 

I am so constantly using the lime-light for lecture 
purposes, that a residue of oxygen is always at hand, 
ready for any home experiment that I like to try ; other- 
wise, I should, perhaps, have decided to carry out my plan 
with some other illuminant. Fitting a blow-through lime- 
jet to an experimental lantern with a 4-inch condenser, 
and with a quarter-plate portrait lens as the objective, my 
optical arrangements were complete. But a 4-inch con- 
denser is clearly useless for projecting the image of a 
negative nearly double its area. My first operation was, 
therefore, to make some small positives on glass from the 
negatives. This was easily done by fitting the negatives 
into my copying apparatus, and using a quarter-plate 
camera. The size of the resulting positives was just two 
inches across ; smaller, it may be thought, than was abso- 
lutely necessary. But, by this plan, I employed the best 
part of the projecting lens, and there was no chance of any 
falling off in sharpness at the margin of the pictures. 

The small positives were made with very great care, the 


exposure and development being so controlled that the 
resulting pictures were somewhat denser than would be 
advisable for an ordinary lantern-slide. They exhibited in 
miniature every detail to be found in the negatives to 
which they owed their origin ; and, in more than one case, 
an improvement was effected in the process of reduction, 
for some of the negatives were yellowed in certain portions, 
and would, therefore, print unequally. This was obviated 
by shading during exposure. 

The positives, although measuring only 2 inches across, 
were taken for convenience on the standard plates for 
lantern pictures, 3 J by 3 J ; so that a broad margin of 
clear glass remained all round them. This was covered 
with black varnish, after which the glasses were fitted into 
the usual grooved carriers employed in lantern work. 

The next thing was to arrange a proper focussing-screen 
for the reception of the image. This took the form of a 
sheet of glass, 16 by 13, covered on one side with white 
paper. Temporary wooden clips, fastened to the wall at a 
convenient height from the ground, held this papered glass 
in position, and in such a way that it could be readily re- 
moved and a sensitive plate put in its place. 

It is with regard to the sensitive plates that I must now 
speak. I found that commercial plates of the size required, 
16 by 13, were very expensive; if I remember rightly, some- 
thing like .2 per dozen was the price quoted to me. This 
was more than I cared to expend on mere experimental 
work ; besides which, it goes against the grain to buy 
plates when one has been in the habit for years of making 
them of unsurpassed quality. I now bethought me that I 


had put away somewhere a jar of chloride emulsion, which 
I had made some months before, and had left neglected for 
want of opportunity to make plates from it. Why, thought 
I, should I not make some 16 by 13 plates with this 
chloride emulsion ? The thing was no sooner conceived 
than put in practice, and that night the plates were coated 
and racked, to the number of eighteen. I also was careful 
at the same time to cover a few quarter-plates, with which 
I could make trial exposures. 

There is one great advantage in manipulating chloride 
emulsion and the plates made from it : it is so insensitive 
about 100 times less so than bromide plates that the 
brightest of yellow lights can be used without affecting it. 
I use a brilliant paraffin lamp, surrounded by a wire fence, 
and this is covered with a screen of yellow oiled paper. 
The light given is so great that a book can easily be read 
at the further end of the room, and my coating-room is 
quite a large one. 

Two days later I was ready for work, and had the 
lantern adjusted at the right distance from my focussing- 
screen on the wall to give an image of the required size. 
Carefully focussing the first picture, I took one of the 
little trial-plates, and held it against the focussing- screen 
for one minute. Upon development it showed under- 
exposure. One or two more trials resulted in my finding 
that the correct exposure was ninety-five seconds. I now 
felt some confidence in dealin^ with the larger plates, and 
I exposed three, one after another. 

Now came the development. 1 mixed, first of all, one 
pint of developer from my stock solutions, and this I put 


into a jug. The first plate was pat into a dish, and the 
whole jugful swished over it. The image flashed out at once. 
This is always the case with my chloride plates, so that it 
did not surprise me. Keeping the developer moving over 
the plate, I lifted up the glass at intervals so as to watch 
its progress. In about four minutes it had attained 
sufficient density. I then emptied the developer back into 
the jug, for I knew it would serve for several plates in 
succession. The negative in the dish was now thoroughly 
washed with about a gallon of water, and transferred to 
the fixing-bath. The remaining plates were then treated 
in exactly the same way, and without a single failure. 

There was at first some difficulty in thoroughly washing 
such large plates, but I solved it by making use of the 
bath-room. The bath was filled with water, and the 
plates were placed along the sides, film-side down. In less 
than an hour they were thoroughly freed of the fixing salt. 

These negatives were all that could be desired. Some 
of them were purposely reversed for printing by the 
carbon process, this reversal being brought about by the 
simple expedient of causing the film-side of the little 
positive to face the light in the lantern. Their perfection 
of detail may be gauged by the following : In one case the 
little positive had become rather dusty previously to 
exposure, and I took it out of the lantern, and rubbed its 
varnished surface with my handkerchief. This caused 
some tiny scratches upon it, which were at the time quite 
unnoticed ; but the scratches were clearly visible on the 
enlarged negatives. They were, certainly, not thicker 
than the finest spider's web, but still, there they were. 



I have already indicated how this work of enlarging 
can be done with an ordinary optical lantern, so long as 
the size of the negative is not above that of a lantern 

FIG. 60. 

slide. For larger negatives it is far better to use a proper 
enlarging lantern of the type shown at fig. 60. 



|P to a recent date the so-called lantern micro 
scope supplied by various dealers was but a toy, 
having all the faults which it was possible to 
imagine in an optical instrument. Moreover, it neces- 
sitated the use of specially prepared objects of large size, 
the wings of insects and the like. But latterly a good deal 
of ingenuity has been expended on the instrument, and it 
has been brought to great perfection. Objects as prepared 
for the ordinary microscope can now be used for projection 
in the lantern microscope, and this one change of the 
conditions under which the instrument can be used points 
to an improvement of no mean kind. 

There are certain requirements to be looked for in a 
really serviceable lantern microscope. The first of them is 
good illumination. The most perfect form of limelight jet 
must therefore be used, and even this, when the higher 


powers of the instrument are employed, is far from being 
enough. The electric light would obviously be the best 
form of illuminant to use for the microscope, but the 
incandescent variety is far too feeble, and the arc form 
possesses neither the steadiness nor the accuracy and per- 
manence of centreing which is so requisite in microscopic 
work. So to the limelight we must at present confine our 
attention, aiding it as far as possible by careful arrange- 
ment of the lenses used in conjunction with it. Hence the 
condenser must be of the best form, and must be seconded 
by a substage condenser suited to the objective or power 
which happens to be used. Provision must also be made 
to filter the light through a layer of alum solution, which 
absorbs the heat rays, and saves valuable objects from 
being destroyed. 

Having secured the brightest light possible, and done 
our best to concentrate it upon the object, we have 
next to consider the best means of forming an image of 
that object upon the screen. An objective may do excellent 
work with the ordinary microscope, bat utterly fails to 
give a satisfactory image on the lantern screen. Perhaps the 
definition in the centre of the disc is satisfactory, but the 
margins are all hazy and indistinct. One may examine a 
large number of objectives with the lantern microscope before 
one is found suited to the work. But makers are now 
giving serious attention to the requirements of the recently 
perfected instrument, and objectives of great excellence 
can be obtained. 

One of the most perfect as well as simple arrangements 
for showing microscopic objects with the ordinary lantern 


is the attachment shown at fig. 61. This contrivance 
may be compared to an ordinary microscope with its tube 
removed, and with the lantern light at the back of the 

FIG. 61. 

stage instead of the mirror. The attachment is fixed 
on the lantern in place of the usual objective, and the 
objects to be shown are supported in a vertical position by 
spring clips. The microscope objective is held, as shown, 
on a movable arm worked to and fro by a milled headed 
focussing screw. At the back of the object is a substage 
condenser, not shown in the cut, and a revolving plate 
with different sized diaphragms. A trough containing a 
saturated solution of alum is placed on the lantern stage 
to protect the objectives from heat. In using the instru- 
ment the limelight must be adjusted in distance from the 
condensing lens for each different power used; and, indeed, 
for every change in the diameter of the diaphragm 
employed. For living objects, such as those illustrating 
pond life, a small tank is used, and is placed against 
the spring clips. The objectives suitable for this form 
of instrument are those which range between 3 in. 



and 4-10ths of an inch. Its performance leaves little to be 

A far more elaborate form of lantern microscope is that 
which is shown at fig. 62, and which has been designed 
by Mr. Lewis Wright. In the opinion of most of our 
eminent microscopists, including Dr. Dallinger and the late 
Dr. Carpenter, this instrument is by far the most perfect 
of the kind ever produced. It is certain that no better 
effects are possible than are produced with high-power 

FIG. 62. 

objectives with this microscope, until the electric light 
may be so perfected as to place a new power in our hands. 
A flea 15 feet long, literally larger than an elephant, is 
shown with this microscope brilliantly and exquisitely 
defined, while the circulation of the blood in a frog's foot 
can be as easily seen as by the table microscope. 
E 2 


The instrument can be made either complete in itself, as 
shown in the cut, or it can be fitted to any good optical 
lantern. In the first case, it is provided with a triple 5-in. 
condenser, which insures the maximum amount of light, 
and in the latter case the lantern condenser, of whatever 
form it may happen to be, is brought into use. The 
illustration gives a very fair idea of this instrument, by 
which the relation of its various parts can be well under- 
stood. It has a coarse adjustment focussing screw, as 
well as one for fine adjustment. The tube in front of the 
objective is for the reception of various lenses to give 
extra amplification, and the necessary alum-tank is let 
into the brass front tube, midway between its supporting 
pillar and the large condensers. The details of the stage 
and revolving diaphragm plate are much the same as in 
the instrument last described, but the substage condensers 
are 'of varying foci, and are suited to the different objec- 
tives employed. The milled head immediately above the 
pillar is in connection with a rack tube, which provides the 
necessary distance adjustment for these condensers. 


It will be at once conceded that most objects, animate 
and inanimate, can be photographed, and that such photo- 
graphs can be used as lantern pictures. But there are 
still others which cannot be so treated, or rather, which 
can be better shown as opaque objects. The worker with 
the microscope will be able to appreciate the possibility 
of showing, by means of the lantern, objects which are 
not transparent. Some of the most beautiful effects 


seen in the microscope are by means of opaque objects 
viewed by means of the spot lens. In like manner we 
can obtain wonderful effects by the use of the opaque lan- 
tern. Let me give one or two examples of the use of such 
an instrument. Suppose that a lecture upon the history 
and construction of the watch is contemplated. How dull 
such a lecture would be if illustrated merely by a set of 
diagrams ! The audience would soon be lost in the maze 
of toothed wheels and springs, and few would understand 
the difference between one movement and another. But let 
the same lecture be illustrated by watches in action, their 
enlarged images thrown on the screen, and their wheels all 
at work, and how differently will the audience regard the 
subject before them. Every tiny screw, the brilliant blue 
of the steel parts, the very grain of the metal is beauti- 
fully shown, while the ceaseless and silent working of the 
mechanism adds greatly to the picture. Coins and medals 
can also be splendidly shown by the same apparatus, and' 
far better than in any other way. Various fruits can be 
shown in section ; a lemon or orange so treated being a very 
curious object, especially if it be squeezed, when the pips 
and juice fly upward, or, at any rate, appear to do so. A 
freshly-opened oyster makes another peculiar object for 
the opaque lantern. These few examples will show that 
this form of lantern is one which can be of great use in 
intelligent hands. It is especially serviceable to the 
owners of cabinets or collections of curiosities, moths and 
butterflies, coins, medals, shells, minerals, &c., which 
cannot readily be photographed, or which it is desirable to 
show with their natural colouring. 


The opaque lantern was first devised by Chadburn, and 
for a long time was known by his name. Its construction 
is simple enough. The object is so placed that it can be 
strongly illuminated by the condensed rays from either 

one or two limelights ; an objec- 
tive lens being used to form the 
image on the distant screen. 
The annexed diagram, fig. 63, 
will explain the relations of the 
different parts of a good opaque 
lantern. LL are the limelights, 
CC the condensers, O the ob- 
jective, and E the object to be 

shown. At one time, a large instrument of this type was 
made for casting the image of a human face on the screen, 
the lenses being of immense size. I saw this instrument 
at work more than once, but its effect was most dis- 
appointing. It certainly was not worth the trouble and 
expense incurred in its construction. It was, of course, 
fitted with a reversing lens, so that the face should appear 
the right way up. The owner of this face, by the way, 
suffered tortures during the short time of exhibition, for 
the powerful limelights close to, and on each side of his 
head, were so hot that they blistered his skin. He was 
made to smile at the audience, and then to drink their 
good health in a glass of wine, a refreshment which the 
poor man really needed after his grilling. 

Under the name of Aphengescope a contrivance is now 
made for fitting on to the ordinary form of lantern, thus 
dispensing with the cost of extra lenses. With a lantern 



thus fitted ordinary carte de visite portraits can be shown, 
as well as the objects already enumerated. Fig. 64 shows 

FIG. 64. 

a modified form of aphengescope fitted to a lantern which 
at the same time is ready to show slides in the ordinary 



manner. It will be noticed that behind the objective is 
placed a sloping mirror, which reflects the light upon the 
card, photograph, or other object above it. The objective 
is then shifted from its usual position to an orifice above, 
which is shown in the cut with a stopper in it. This 
lantern the design of Laverne & Co. is lighted by a 
mineral oil-lamp, but, obviously, the limelight could be 
adapted to it. Mr. Medland, of the Borough, has intro- 
duced a lantern on the same principle, see fig. 65. So much 

FIG. 65. 

light is necessarily absorbed by the arrangements of the 
opaque lantern, even in its best forms, that the brightest 
of illuminants must be secured to give it full effect. 
It is on record that some years back a form of opaque 



lantern was used in an American Law Court to demon- 
strate to a jury the manner in which a document had been 
tampered with by a forger. Illuminated by a strong side 
light, the magnified image showed clearly where the tex- 
ture of the paper had been disturbed, both by erasure and 
by the action of chemicals. 




LANTERN, as supplied by the dealers, is with- 
out any means of holding the slides during 
exhibition. The slide stage is there, but it is 
about 4J inches in height, while the slides themselves 
are 3^ inches square. To obviate this difficulty, it 
becomes necessary to fit this stage with a wooden 
contrivance called a slide carrier, which can be pur- 
chased of many different patterns. Professional exhi- 
bitors use a wooden frame for each separate slide, but 
this plan is both inconvenient and unnecessary for the 
amateur. Besides which it is positively a bad plan for the 
user of a single lantern ; for as each picture is removed, 
and another one put in its place, the screen is left bare 
while the transfer is effected. This not only has a bad 


effect, but it is distracting to the audience. Moreover, the 
pictures suffer, for they compare disadvantageously 
with the far brighter white disc by which they are 

I can recommend two forms of carrier which obviate 
this difficulty. The first is a grooved frame, open at either 
side, with a travelling tape in the lower groove, which is 
put in motion by a winch handle. The slides move 
through the lantern one after another, like a panorama, 
but care must be taken that they are not allowed to fall 
out and get broken as their time for exhibition expires. 
The other form which I recommend is quite different in 
principle, and of the two methods I prefer it. In this 
latter carrier there is a kind of central frame which 
is accurately adjusted to the lantern stage. Within it, 
and moving freely from right to left, is a double carrier, 
holding two pictures side by side. While one picture 
is being shown, the other is being changed, the right 
and left hand carrier being used alternately. The sole 
objection to this form of carrier is the necessity for 
the exhibitor to reach over his lantern so as to change 
every other picture, which is a slightly awkward thing to 

A modification of this sliding principle, which consists 
of a double changing stage, working vertically, has been 
introduced, but I fancy that the lantern must be con- 
structed purposely for it. I mean that it is not sold as an 
independent carrier, which can be fitted to any existing 
lantern. This consideration, of course, greatly limits its 


Whiting's patent arrangement for facilitating the ex- 
hibition of slides is extremely ingenious, but seems to me 
to be an adaptation of Samuels' changing box, for photo- 
graphic cameras. At any rate, the same principle is 
involved. It consists of a pusher of wood working be- 
tween grooves on the lantern stage. Close against it is a 
box of slides with a powerful spring at the back of them, 
so that they are forced up against the pusher, the front 
one being always in the right position to be pushed for- 
ward on to the stage. The act of moving the pusher 
sends a picture on to the stage, removes that previously 
shown, which goes into another box, or drops down an 
inclined plane out of the way, and at the same time the 
lens is covered so that there is momentary darkness on 
the sheet. This darkness is, I think, preferable, and less 
trying to the eyes of the audience than if the actual 
change of picture took place visibly. 

Other forms of carriers provide in a different manner 
for the lens being covered at the moment of change. One 
very good one consists of a pair of wings, which open and 
close automatically over the front of the objective lens 
as the change is made. In this case the first picture 
seems to darken down on the screen towards the centre, 
'the reverse action immediately discovering the next 

The following remarks, which were written by me, and 
were published in the Yearbook of J ^ holography -, will 
describe the kind of carrier which I myself use : " When 
a man is in the habit of travelling about from place to 
place on lecturing intent, he will, if wise, reduce his 


.impedimenta in the shape of lantern and lantern belongings 
to the smallest possible bulk consistent with efficient work. 
As much of my time has been and is spent in this way, 
I have given a great deal of thought to this matter of 
reduction of bulk, aud have achieved some little success in 
it. But it is only to one particular point that I now wish 
to draw attention, and I do so in the hope that what I have 
done may be as useful to others as it has been to me. In 
the first place I think that all lecturers will agree that each 
lantern picture should be fitted in a carrier of its own. The 
various forms of panoramic and shifting carriers which are 
fixed in the lantern while the glass pictures are passed 
through them at the time of exhibition are all very well 
for home use and private work, but in my opinion are not 
suitable for employment in public halls. I need not name 
all my objections to them, for one will suffice. The 
pictures are not sufficiently protected from breakage, and 
the risk of breakage, even of one slide out of a set, is a 
thing not to be thought of by a good exhibitor. At first I 
used 7 by 4 mahogany-grooved carriers for all my pictures, 
but I found that they were objectionable, on two grounds : 
one of these is that they readily break, and the other is 
that in packing they take up far too much room. It was 
to obviate these difficulties that I designed the carrier now 
to be described, and which I have had in constant use for 
three years with every success. My only objection to it is 
the necessity for making it myself, which is perhaps no 
real objection at all, for a little carpentry forms a healthy 
relaxation to one whose occupations are chiefly of a seden- 
tary nature. 



My slide-carrier consists of a piece of wood 7 inches long 
and 4 inches wide, with a square opening in the centre to 
receive the glass picture of the standard size, 3^ by 3 J 
inches. This is faced on each side with a piece of card- 
board, the opening of which is so much smaller as to form 
a rebate in which the picture rests, and from which it 
cannot fall out. 

And now to describe the method of manufacture. First 
procure two pieces of sheet zinc, each measuring 7 by 4 inches 
outside, but having openings of slightly different areas. 
These are indicated in the annexed cut (fig. 66), the opening 

- *7J * 

FIG. 66. 

in one piece of zinc being shown by unbroken lines, and in 
the other by dotted lines. It is best to make these patterns, 
in the first instance, in thin card, and to hand them to a good 
workman to copy in zinc. (I may mention in parenthesis 
that here I found my chief difficulty. The average British 
working man who has been brought up in the zinc industry 


can make a first-rate chimney-pot, but when out of the 
chimney-pot groove he is rather at sea. If he tells you that he 
can cut out in zinc your pattern correctly, " Trust him not, 
he's fooling thee " ; at any rate, carefully check his work, and 
you may find it out a trifle, and this trifle when magnified 
in the lantern is no trifle.) With correctly-cut zinc patterns 
you can get through the work of making carriers very 
quickly. The pattern with the larger opening may be 
labelled W, for it is for wood only, and the other labelled 
C, for cardboard. 

The wood to use is the best pine, which in thickness 
should approximate to the average lantern slide, say one- 
eighth of an inch. This can be obtained at any good saw- 
mills. Laying the zinc pattern on this, and pencilling 
by its aid, a whole board can be quickly marked out for 
cutting. This cutting can be easily accomplished by using 
a sharp shoemaker's knife. The cardboard can be of the 
thinnest description, and this, too, can be cut in the same 
manner, using the zinc pattern designed for it. With 
several wooden pieces ready cut, and double their number 
of cards, you may now proceed to put them together. With 
good hot, but thin glue, paint over one surface of the wood, 
and press one of the cards upon it, taking care that the 
centres of the two agree. Place the joined pieces on your 
work-table, with a heavy, flat weight above them ; when 
No. 2 is similarly treated, place it also under the weight, until 
you have a goodly pile of pieces of wood faced on one side 
with card. Leave them for the night. The next opera- 
tion is to place a glass picture in each half -formed slide, 
and to glue the cardboard face to each. Once more the 


hot glue and weight operation must be repeated, until the 
batch, say two dozen slides, is complete. When com- 
plete, this batch, with a piece of blank board at each end 
of the pile, may be screwed up between a couple of car- 
penter's cramps, and left before the kitchen fire all day or 
all night, until the glue is thoroughly hardened. When 
quite dry and hard the slides may be separated and again 
arranged between the cramps, in such a position that their 
edges can be run over with a sharp plane. After this they 
can be separately rubbed on every edge with glass paper, 
and, when dusted, they are finished. 

The advantages of these carriers are many. Firstly, 
you may drop one from a height of 6 feet from the floor 
with absolute impunity. Secondly, if the zinc patterns 
be correctly cut, the slides will register correctly with one 
another. Thirdly, six dozen, which is about the usual 
complement for a lecture set, will pack in the space 
occupied by three dozen under the old system. The sole 
disadvantage pertaining to these carriers is, that the pic- 
tures cannot be readily shifted from one to another. The 
remedy is obvious. For lectures of an ephemeral cha- 
racter, I mean for those the subject of which is merely 
of passing interest, use the old form of carrier, but for , 
more permanent ones adopt mine. 


It is given to a few to know what it is to arrive at a 
schoolroom or other lecture-hall in some remote country 
district, and to expect to find a few conveniences ready to 
hand. The first thing to ask for is a table, upon which 


can be placed the lantern-box, while the lantern itself com- 
monly screws to the top of the said box. There is always 
a difficulty in finding the right kind of table. It is either 
too small or too large, or else it is rickety and unsafe, or 
perhaps it is too beautiful to be devoted to such a heathen- 
ish purpose as the support of a lantern-box, all which 
things happened to me and my assistant times out of 
number, until I invented a lantern-support for myself, 
consisting of four iron legs. With them> I can now laugh 
the decrepit local table to scorn, and the beauty of the 
leather-covered library specimen, which must not be 
touched by sacrilegious hands, is a thing which ceases to 
interest me. In a word, I am independent of such primi- 
tive supports, and am as proud of my iron legs as is a 
Chelsea pensioner of the wooden understandings which he 
exchanged in the Crimea for those with which he was 

The accompanying sketches will in a moment cause the 
form and purpose of these legs to be understood. They 
are made of iron, having a sectional area of 1 inch by 
three-eighths of an inch. Each fits into a socket upon the 
lantern box, and each has at its lower end a kind of flat 
toe turned outwards, through which is a hole by which 
the leg can be screwed to the floor. This, however, is 
hardly necessary, for the weight of the lantern and its 
box, together with the slides which it contains whilst in 
use, are quite sufficient to make the whole arrangement as 
firm as a rock. 

In the annexed cut (fig, 67) A is the lantern box, fitted with 
a strong frame at the bottom, F, upon which the sockets can 




be screwed. L is one of the legs in position. T is an 
enlarged view of the toe of one leg, showing the screw- 
hole where it can be attached to the floor. A 1 is a socket, 

FIG. 67. 

showing how it is composed of two pieces of iron, one flat 
and one bent. I may mention that the top of the leg, 
which fits into the socket, is diminished in size for that 
purpose, and that the shoulder thus formed on it holds it 
firmly in position. I have used these legs for several 
years, and have never seen anything which would fulfil 
their purpose so well. They can be secured for travelling 
by a couple of leather straps, or can be made to go inside 
the lantern-box. Their combined weight is fourteen 



Photographic negatives for lantern slides should be 
rather less dense than those used for ordinary printing 
upon paper : hence it is better to take negatives for the 
purpose than to utilise others which have been taken for 
ordinary reproduction. The lesser density must be gained 
by stopping the development judiciously, and not, of 
course, by checking the exposure. There are many 
cameras now to be had which take small negatives suitable 
for lantern work. These are so compact and self-contained 

FIG. 68. 

that they require no stand, focussing-cloth,, or other adjunct, 
and will readily pack away in a portmanteau or box 
without inconvenience to the traveller. The author has 
used a camera of this description with great advantage, and 
has taken many dozens of instantaneous pictures with it. 

A useful form of hand-camera introduced by the 
Stereoscopic Company is here shown (see fig. 68), 



Another camera which is made purposely for lantern- 
slide negative making has been recently introduced by 
Messrs. Mayfield & Cobb. This will, when folded up, easily 
go into the pocket, and is used like the last-described 
whilst held in the hand (see fig. 69). 

FIG. 69. 

A great deal of attention has lately been aroused with 
respect to so-called detective cameras. They would perhaps 
be better described as concealed cameras, for there are many 
reasons why they cannot, except by some happy conjunc- 
tion of circumstances, be used in the detection of crime. 
Their manufacture has certainly been brought to grea^ 
perfection, and a wonderful amount of ingenuity has been 
displayed in their construction. From experience I can 
speak most highly of the good pictures which can be pro- 
duced by them. But one essential condition must not be 
absent; such pictures want absolute sunshine. I give 
three examples of these detective cameras. The first, 
Watson's (fig. 68), is a leather-covered box, containing as 



will be seen by the dotted lines, a complete camera. This 
camera can be focussed and manipulated altogether by 
touching buttons on the outside of the box. 

FIG. 70. 

Next I notice Marion's Parcel Camera (fig. 71), which 
is of different construction altogether. It consists of a 
covered box, like a parcel, but this box forms the camera 
with a lens in front concealed by a paper flap. The 

FIG. 71. 

illustration shws the appearance of the underside of the 
box, with a slit at one end for the reception of the sensitive 
plate and the instantaneous shutter apparatus at the other 
end. The plate is contained in a bag of the shape shown 



at fig. 72, which locks on to the aperture in the bottom of 
the box, when a plate has to be transferred from one 
to the other. I have found both these cameras to work 

FIG. 72. 

The newest arrangement of the kind is the Kodak 
Camera introduced by the Eastman Company (see fig. 72). 
In this small box a hundred pictures can be taken by 
the simplest possible movements. It contains a ribbon 
of sensitive material, which is used panorama fashion 
instead of glass plates. 

FIG. 73. 

I am convinced that there is a very great future before 
these detective or concealed cameras. That they will pro- 
duce negatives of first-class quality, I have proved again 



and again, and it is the thought that such negatives can be 
so readily made to give lantern slides, or can be used for 
enlarging purposes with the help of the lantern, which has 
induced me to give this brief notice of them in my chapter 
on lantern accessories. 



j 1ST the foregoing pages I have endeavoured to 
describe the best methods of manipulating the 
lantern ; and I hope that I have done so in such 
a manner as to enable all my readers readily to under- 
stand the working of this beautiful instrument. I feel 
convinced that if my * instructions are carefully followed 
all will go well, at all events, in the apparatus depart- 
ment. But the best instrument is no good unless the 
lecturer be an efficient showman and speaker. Unfor- 
tunately many essay the task of lecturing who are physi-, 
cally unfit for it. There are many good-natured people in 
the world who will undertake, very often for some charity, 
to act as lecturer in a school-room, the slides being 
borrowed from some optician with a printed lecture fitted 
to them. This good-natured man will take up the work 
without much thought or consideration, and the result is 
too often a very bungling performance. A man may have 


a fund of knowledge, but lack the power of imparting it to 
others. The fault is common enough in the pulpit, where 
it is often the case that a clergyman who has won high 
honours at the university, and as a reward for his scholar- 
ship finds himself in due course incumbent of a living, is 
an utterly incapable speaker, greatly to the distress of his 
congregation. He can of course compile or write a good 
sermon ; that is to say, a discourse which is carefully con- 
structed and perfect as a specimen of written English ; but 
when he gets into the pulpit he reads it out in such a 
droning voice, and with such a lack of emphasis, that many 
of the congregation dose off into peaceful slumber. Many 
lecturers have the same want of ability, and it is this 
circumstance that has had the effect more than any other 
of prejudicing people against a lecture, as a thing which is 
necessarily dull and the reverse of entertaining. 

More than once it has fallen to my lot to lecture in some 
hall which is strange to me, and on such an occasion 1 have 
generally asked the hall-keeper if a large audience may be 
reasonably looked for. The answer is too often something 
like this : " Well, sir, the people hereabouts don't much 
care for a lecture ; but last Saturday night the place was 
crowded from floor to ceiling." " Dear me ! " is my answer, 
" and who was the lecturer on that occasion ? " " Lor' 
bless your soul, sir, it wasn't no lecture, it was niggers." I 
leave my readers to imagine with what feelings I looked 
forward to the pleasure of meeting my audience. 

A lecture entertainment will fail sometimes owing to the 
total incapacity of the speaker, to his bad articulation, 
nervousness, lack of voice, or want of tact in dealing 


with the audience. Still more often failure is due to bad 
arrangement of the matter which the lecturer has under- 
taken to deliver. The remedy for this last fault is 
obvious, namely, a course of training in the reading of 
standard works. Some may perhaps think I am recom- 
mending an old-fashioned book, when I name " Blair's 
Lectures on Rhetoric," as a very valuable aid to the writer 
and speaker. I would advise all beginners to write their 
lectures and go over the matter again and again, before 
trusting themselves on the platform ; and in constructing 
the fabric of their discourse, let them remember that the 
sentences should be as a rule shorter than if the words were 
merely intended for the eye of a reader. A sentence con- 
sisting of several lines without any full stop, although it 
may pass in ordinary composition, is very tiresome to listen 
to ; a most attentive audience will, by the time the verbose 
paragraph ends, forget its opening, and the sense be 
consequently lost. Again, in composing a lecture which 
is illustrated by lantern pictures, care must be taken to so 
arrange it that the pictures come in naturally, and are not 
dragged in willy-nilly, as if they were in stock and must be 
shown at any price. The views should be the best of their 
kind, but must be altogether subservient to the text. If a 
part of the subject is of such a nature that it may be likely* 
to prove tedious to an audience, and audiences differ 
amazingly in their receptive faculties, that part should 
either be compressed, or it may be lightened by a good anec- 
dote, or even by some illustration which will raise a laugh. 
Such pictures introduced with circumspection are most 
useful ; but the power of employing them should be used 


sparingly. Let the lecturer look upon them as the high- 
lights of a work of art. The novice with a brush will daub 
such high-lights on every projecting corner of the compo- 
sition, until the beauty of the whole is lost in their glare ; 
a true artist, on the other hand, will deftly put in a touch 
here and another there, with the result that the whole work 
is brightened and generally improved. 

The grosser faults into which a novice in lecturing is 
apt to fall are generally the result of simple inexperience 
or carelessness. He should make it a golden rule that 
whatever may occur he must not lose his temper. In the 
ordinary affairs of life, the man who can control his temper 
has always the best of an argument ; and still more so is 
this the case on the platform (and on this platform, let 
us remember that there are often some very trying inci- 
dents to deal with, particularly amid the darkness of 
lantern illustrations). I once found it very hard to control 
both my sentences and my temper, when I became aware 
that I was a target for some mischievous boy's pea-shooter; 
but on politely addressing the unseen youth, and telling 
him that I knew he was a very smalllooj, and that therefore 
I could excuse his childish conduct, but at the same time he 
must keep his peas in his pocket, the nuisance stopped. I 
recently heard of a case where an inexperienced lecturer 
was loudly told more than once to " speak up." Instead of 
taking this invitation as a valuable hint, and acting upon 
it as he should have done, he retorted rudely, and the audi- 
ence refused to listen to him any longer. It is to be hoped 
that he will not again attempt work for which he is 
evidently quite unfitted. 


Iii lectures of a popular and entertaining character, 
it is often desirable to introduce a little music; but if 
this is done at all it should be done well, the lecturer first 
of all satisfying himself as to the capabilities of the 
musician. They should then arrange together where the 
music is to come in, and the player should have furnished 
to him by the lecturer a set of cues, with hints as to the 
nature of the music to be played at the occurrence of those 
particular words. To show that this precaution is not an 
idle one, let me state that recently I heard a lecture de- 
livered in which a few bars of music came in at stated 
times. On one of those occasions the lecturer was showing 
a tomb erected to the memory of some celebrity who had 
recently departed. He described this tomb and said a few 
touching words with reference to the high character of the 
departed one ; and, he had no sooner finished, than the 
pianist at his elbow struck up a merry waltz ! 

The lecturer should be careful to select an intelligent 
operator. The man employed should be one capable of 
concentrating his attention upon the work which he has 
to do. The gases will require attention, the lime wants 
turning every few minutes, or the light from the lantern 
soon drops; but, at the same time, too much should 
not be thrown upon the hands of the operator; for in- 
stance, the lecturer should make it a standing rule to go 
carefully through the slides which are to be shown before 
the lecture commences, so that each one is not only in its 
proper place, but each is so arranged that the operator will 
hardly be able to put one in the lantern except in its right 
position. A landscape, or more especially a portrait, ap- 


pearing suddenly on the sheet standing on its head, is an 
episode which disturbs both lecturer and audience, and 
will, for a time, entirely break the thread of the discourse. 
This can easily be avoided if the slides be marked in a 
certain way. If the slides are being used in fixed carriers, 
and are therefore simply in the form in which they are sold 
at the shops, each one should be marked with a white disc 
at the lower left-hand corner of the picture, taking care 
that the wafer is on the face of the picture, and by pre- 
ference, beneath the cover glass, so that it cannot be rubbed 
off. This white wafer will then come conveniently below the 
operator's thumb when the slide is in its inverted position, 
as it should be, before being placed in the lantern. 
The operator will then become accustomed to look for this 
white dot, which he can easily see even in a darkened 
room, and he will place his thumb above it, and the picture 
will of necessity appear on the sheet, as it should do. If 
the back of the picture is placed next the light, of course 
everything on the sheet appears in reversed order. What 
should be the right hand of the picture appears on the left 
of the sheet, and vice versa. This is of no great conse- 
quence in some cases ; but if the picture should include 
any lettering, such as that on a sign -post or a shop-front, 
these letters will appear backwards, and the fault is at 
once detected by the audience, and commented on by them 
in audible whispers. I once had a volunteer assistant who, 
at short notioe, supplied the place of my regular operator, 
who happened to be ill. In the middle of my lecture this 
man showed a slide upside down ; on seeing his mistake, 
he took it out of the lantern and put it in again sideways. 



He again saw the error, took it out of the lantern, and re- 
placed it, but on its other side ; so, in reality, this genius 
tried every conceivable way of showing 
that picture but the correct one. 

It is imperative that there should be 
some well-understood code of signals be- 
tween the lecturer and the lantern operator, 
for in many cases they are 50 feet apart. 

Some lecturers are content with verbal 
directions, but these are simply intoler- 
able to any one with any idea of what 
a lecture should be. To hear a man 
calling out, " Next picture, please," and 
so on, utterly spoils even a lecture which 
is good in other respects. An audible 
sound signal, such as tapping with a 
pointer, or sounding a gong when the 
picture is required to be changed is 
almost as bad. A lecture lamp has 
recently been introduced, which not only 
comprises a shade light for the lecturer's 
desk, but has at the back, i.e., the side 
presented towards the audience, and there- 
fore towards the lantern, a little disc of 
red glass, which is uncovered by touching 
a lever at the side of the lamp. See S, 
fig. 74. When the operator sees the little red flame dis- 
closed he knows that a fresh picture is wanted, and should 
he be inattentive to that signal there is a little gong, B, below 
the lamp which can be used on such an emergency. This 

FIG. 74. 


lamp is portable, convenient, and efficient. But above all 
devices for signalling I prefer a simple electric arrange- 
ment. The one that I am in the habit of using consists of 
a single-stroke electric bell with the gong removed from it. 
When the current is sent through the coils of the attached 
magnet, the armature is of course attracted, and a little 
tap is heard, which, although quite unnoticed by the 
audience, is easily heard by the operator, who is on the 
look out for it. I used to employ in connection with the 
bell, if bell it can be called, a Leclanche battery which 
was placed just below my reading-desk. While on the 
desk itself I had an ordinary bell push, connected with 
both bell and battery. But this arrangement I have since 
superseded by a better one. The Equitable Telephone 
Company have brought out an electric bell which is quite 
independent of battery power, a small magnetic arrange- 
ment taking its place. This generator, as it is called, is 
shown at fig. 75. It acts most perfectly, and is destined, 
I should presume, to work a revolution in electric bell 
mechanism generally. The only inconvenience in the 
arrangement is the difficulty that is sometimes found in 
carrying the wires between the lecturer and the lantern, 
and so concealing them or putting them out of reach 
that there is no chance of their being tampered with by 
mischievous hands. In a lecture theatre, where there is 
commonly a gallery, the wires can be run round the 
front of the balcony quite out of sight. In other cases 
they can be laid on the floor underneath the carpet or 
matting. In nine cases out of ten there is no difficulty 
in adjusting them. The signal should be given about 


half a minute before the change of picture is really 
required, 59 as to give the operator time for the necessary 
manipulation. He should be instructed when to dissolve 
the view slowly, should he be using a double or triple lan- 
tern, and when to make the change quickly. To dissolve a 
diagram or a portrait is ridiculous, and sometimes leads to 

FIG. 75. 


very comical effects. I remember once attending a lecture 
where a number of illustrations were shown of different 
types of national costumes. First of all there came a 
woman in peasant's dress. This was followed by a man 
whose lower extremities were clothed in tight-fitting white 
unmentionables. It so happened that one figure occupied 
on the screen exactly the same place as the other, so 


that when the lady was slowly dissolved into the gentle- 
man, the astounding effect was produced of .her clothes 
gradually melting from her form. 

I must now bring my remarks to a conclusion, with 
the hope that many will find my book useful. If the 
word Ego has crept in with too much persistence, I trust 
that my indulgent readers will impute it rather to personal 
acquaintance with the things of which I write than to any 
less worthy source. 


ADVANTAGE of pure hydro- 
gen, 69. 

Aniline colours, 161. 
Aphengescope, 246. 
Astrometeoroscope, The, 180. 

BELL, Electric, 271. 
Biunial, Detachable, 13. 
Biunial lantern, 8. 
Blow-through jet, 53. 
Boards, Double, 62. 
Brass work, Superfluous, 10. 
Brewster, Sir David, 5. 
Brin's Oxygen method, 46. 

CAMERAS, Detective, 260. 
Camera for microscope, 215. 
Cameras, Hand, 259. 
Capacity of cylinders, 49. 
Carriers, 250. 
Cellini, 1. 
Choreutoscope, The, 180. 

Clamp, Steward's, 56. 
Clouds, 164. 
Clouds, Printing, 233. 
Cohesion figures, 175. 
Collodio-bromide process 111. 
Colosseum, 1. 
Coloured gelatine, 188. 
Colouring lantern slides, 145. 
Colours, Complementary, 166, 

Colours used for slide painting, 

Complementary colours, 166, 

Compound frame for copying, 


Compressed oxygen, 48. 
Condenser, Dallmeyer's, 23. 
Condensers, 21. 
Copying apparatus, 124. 
Copying paper prints, 121. 
Current reverser, 173. 



Cutting masks, 142. 
Cylinders, Capacity of, 49. 
Cylinders for gas, 48. 

DALLMEYER'S Condenser, 23. 
Decomposition of water, 192. 
Desk for slide painting, 148. 
Detachable biunial, 13. 
Detective cameras, 260. 
Developers, 120, 121. 
Development, 119. 
Development of photograph in 

lantern, 199. 
Dissolver, 9, 80. 
Distance between lantern and 

sheet, 95. 

Distances, Table of, 96. 
Double boards, 62. 
Drummond Light, 5. 
Drying-rack, 136. 
Dry plate slides, 109. 

EASEL for enlarging, 224. 
Electric Bell, 271. 
Emulsion, Filtering, 132. 
Emulsion making, 128. 
Enlarging lantern, 239. 
Enlarging photographs, 222. 
Enlargements, 209. 
Equivalent focus, 95. 
Ether-oxygen light, 83. 
Experimental lantern, 190. 
Experiments with tank, 193. 
Exposing gauge, 229. 
Exposure, 117. 

Exposures for enlargements, 

FILTERING Emulsion, 132. 
Frame for sheet, 93. 
Frogs' legs, Projection of, 

GAS-BAGS, 58. 

Gas bottles or cylinders, 48. 
Gelatine process, 115. 
Gelatino-bromide paper, 225. 
Gelatino-chloride plates, 133. 
Glass grinding, 101. 
Ground-glass lantern slides, 


Ground-glass varnish, 102. 
Gauge for exposures, 229. 

HAND Cameras, 259. 
Hanging the sheet, 88. 
Hints, Practical, 264. 
Home-made gelatine plates, 

Hydrogen generator, 69. 

ICE experiment, 197. 
Iceland Spa, 187. 
Intensifying, 140. 

JET, Blow-through, 53. 
Jet, Mixed, 53. 
Jet, Oxycalcium, 50. 

Kircher, 3. 

LAMP, Newton's, 6. 
Lantern and Photography, 
The, 204. 



Lantern, Biunial, 8. 
Lantern enlarging, 239. 
Lantern enlargements, 209. 
Lantern for experiments, 190. 
Lantern, How to work, 76. 
Lantern legs, 256. 
Lantern microscope, 240. 
Lantern, Mineral Oil, 7. 
Lantern, Opaque, 244. 
Lantern-slides, 97. 
Lantern-slide colouring, 145. 
Lantern - slides from paper 

prints, 121. 
Lantern slides on dry plates, 

Lantern-slides on ground 

glass, 99. 
Lantern-slides on wet plates, 

Lantern-slides with transferro- 

type paper, 143. 
Lantern, Triunial, 15. 
Lecture -lamp, 270. 
Lenses, Condensing, 21, 23. 
Lenses, Objective, 26, 27. 
Lens, Supplementary, 22. 
Limes, 71. 
Lime-shield, 57. 
Limes, Preserving, 74. 

MAGNETIC experiments, 201. 
Making emulsion, 128. 
Making oxygen, 30. 
Masks, Cutting, 142. 
Micro, Attachment, 220, 242. 
Microscope, Camera for, 215. 
Microscope, Lantern, 240. 
Mineral oil lantern, 7. 

Mixed jet, 53. 
Mixture, Oxygen, 40. 
Moonlight pictures, 159. 
Mounting, 141. 

NEWTON'S Lamp, 6. 

OAKLEY'S regulator, 64. 
Objective lenses, 26, 27. 
Opaque lantern, 244. 
Opaque lantern, principle 

of, 2. 

Optical system, 16. 
Oxy calcium jet, 50. 
Oxygen, Erin's method, 46. 
Oxygen, Compressed, 48. 
Oxygen-ether light, 83. 
Oxygen making, 30. 
Oxygen mixture, 40. 
Oxygen retort, 32. 

PAINTING with aniline colours, 


Photographs, Enlarging, 222. 
Photo-micrographs, 211. 
Portable frame, 93. 
Practical hints, 264. 
Preserving limes, 74. 
Pressure boards, 60. 
Primitive lime-light, 51. 
Printing clouds, 233. 
Prism, The, 182. 
Pure hydrogen, Advantage of, 

Purifier, or Wash-bottle, 37. 

BACK, Washing, 136. 
Regulator, Oakley's, 64. 
Ketort, Oxygen, 32. 



SAND - GLASS, Projection of, 


Sciopticon, 6 
Screens, 86 
Sheet, Hanging, 88 
Short-focus lens, 138 
Signalling, 271 
Simple regulator, 68 
Sir David Brewster, 5 
Sky, Treatment of, 139 
Slides by contact, 137 
Spectrum slides, 186 
Steward's clamp, 56 
Steward's regulator, 68 
Superfluous brasswork, 10 
Supplementary lens, 22 
Support for lantern, 256 

TABLE of distances, 96 
Tank experiments, 193 
Tannin process, 110 
The Astrometeoroscope, 180 
The Choreutoscope, 180 

The Galvanometer-slide, 171 

The Kaleidotrope, 179 

The Prism, 182 

" Toilers of the Thames," 

Treatment of sky, 139 
Triunial dissolver, 81, 82 
Triunial lantern, 15 
Tubes, 76 
Tyndall's ice experiment, 197 

USE of condenser, 18 

VERTICAL attachment, 12 
Vortex rings, 191 

WASHBOTTLE, or purifier, 37 
Water, Decomposition of, 192 
Wet Collodion-slides, 104 
Whitewashed screen, 91 
Woodbury-type process, 113 
Working the lantern, 76 










With all ihe Latest 




240 PAGES, 

Just Published, 




406-457, STRAND, & 54, CORNHILL, LONDON. 





Lantern and Transparency 

T> Y a peculiar and quite novel combination of the haloid salts of 
*-* silver, we have produced in Gelatine an Emulsion which throws 
all previous efforts in this direction into the shade, and is pro- 
nounced by all who have tried it a perfect substitute for Collodio- 
Bromide in Lantern and Window Transparency Work. 

All Tones are easily obtainable, from a rich velvety black to a 
delicate pink. 

For Micro-Photography, Copying, and Enlargements, it 
is all that can be desired. 

Prices, LANTERN PLATES, 3i by 3i, Is. per dozen. 

All other sizes coated and charged at the Pall Mall 
Extra-Rapid Prices. 

Pot or Flashed Opal, or a fine ground glass, coated to order at 
shortest notice. 



Factory Thornton Heath, Surrey, 




S 3LI 3D E S. * 

UJ 1 

and is enabled to make and sell Magic Lanterns and Slides Cheaper than 
any other House in the Trade? 

BECAUSE, making this business his Entire Occupation and Study, he is 
able to produce the Best Magic Lanterns and Slides at such Moderate 
Prices that other houses Cannot Compete. 


Upwards of 8O,OOO always in stock. 

7TTITHOUT DOUBT the Best and cheapest House in the World for everything 
Vll connected with Magic Lanterns and Slides. Thonsands of Slides and 
Lanterns Second-hand. Great Bargains. For good quality of Articles, moft 
moderate Prices, and Promptness in Despatch, WALTER TYLER cannot be 
surpassed. ^^^^^ _ ~^~~^~^- 

Send for Illustrated Catalogues and Second-hand Lists, which 
will be sent post free. 




a 2 


G. 8. MARTIN, 







MAGNESIQM FLASHER, for Night Photo- 
_ graphy (or " Stage Lightning ") 4/6. 

LANTERN TRANS PARFNCTES pr^rpd from Pictures, Drawings, Ac. 

Or C.O I r\v>L.CLO 1 LONDON, E.G. 

(Under Sirkbeck Institution, approached by Ch'inrery-la>-e w FMer-lane). 






HINl'ON'S PHOTOGRAPHIC MATERIALS are used by the most 

Successful and Advanced Photographers. 
HINTON'S LANTERN CAMERA, with 12 double backs, Lens, Cloth Case, 

and Stand complete. .Price 7- 

HINT ON'S COLLEGE LANTERN, 4-inch condenser, 4. W ick lamp, best make 
throughout. Is aoapted to take lime-light fittings. Price 3. 17s. 6d. 

Note the Ad dress -38, BEDFORD STREET, STRAND, W.C. 

Pharmaceutical, Operative, and Photographic Chemists. 



Discounts (for the Trade ONLY) 





THE above diagram is a full-sized combined lantern. 

^ It is made of japanned metal. It may be used 

x^7~4w n-^k one ab jre the other, as the dotted lines show, or side 

by side as the positive diagram shows t or, again, the 
two instruments may be separated and worked in two 
distinct places, as each lantern is complete in itself. 
A further advantage is possessed by this lantern, for 
the bodies, which are constructed to accommodate lime- 
light, will alscj readily accommodate : oil-lamps, the 
grooves into which the trays are inserted bciug made 
I to the same gauge as our lamps. 

" It will at once b<* seen this makes the apparatus & 
most desirable one for those who let out on hire, since 
it adapts itself 10 every variety of exhibition. The 
price includes 4-inch Compound Condensers and 
superior Portrait combination front lenses (which 
give splendid marginal definition). We believe this form to be thoroughly 
efficient, consequently strongly recommend it. 

Without Lamps or Jets 5 ft O 

3-wiek Lamps, each O 12. 9 

Gas Jets O 11 O 



Free from complication, free from danger, 
1. 13s, 


Superior Hand-Painted Magic Lantern SLIDES, 

The productions of the eminent firm of 

CARPENTER & WESTLEY, Regent St., London, 

Who desire to reduce their exceptionally large stock, which has always ben 
regarded as the first in the world for ARTISTIC MERIT, whilst for 
Brilliancy and Transparency of Colour the pictures are unrivalled. 

Every requisite for Magic Lantern at lowest possible 
Manufacturers' Prices. 







Manufacturer & Publisher of Magic Lantern Slides & Readings. 

Catalogues on application. Sample Slide and Catalogue for Is. 6d. 

Silver Printing and Transparencies from the Negatives 

of Amateurs. 


The Lenses we hive designed for this purpose are the outcome of a long and 
interesting experience of Lantern work. They hive a full aperture of f/4, and their 
power of definition and flatness of field are excellent. 



Approximate distance from 
screen to cover. 

Diam. of 


12 ft. sq. 

15 ft. sq. 

20 ft. sq. 


6 in. 


30 ft. 


2 in. 






54 ft. 

2* in. 



10 in. 




3 in. 


The Original Five-wick Lantern. For Opaque Objects, Carte-de-Visites, and Ordinary 
Slides, without change of Apparatus. Arrangement in chimney to prevenc smoke 

and regulate lamp. 
The only Lantern which can be changed to exhibit Opaque 

Objects in One Moment. 
Price, complete in Strong Iron Case, 5. 

Fwilparticula.r,v;ith:numerou*te*tin>onialg, .Tree. Medland'g Catalogues of Lanterns t 
Transparencies, Photo. Goods, Microscopes, if Electric Apparatus, now ready. 







Is ttie smallest, lightest, and simplest 

for the ten operations necessary with 


REQUIRED. Size 3^ by 3! by 6J inches. 
Makes ICO 

of all Detective Cameras 
most Cameras of this class 
Weight 35 ounces* 


Developing 12 at once. Drawing off Exposed Films. 

Twelve Negatives are developed at one time. 



EASTMAN DRY PLATE & FILM CO., 115, Oxford Street, London, W. 



Have proved by Public Competition to be superior to all others. 

Awarded Prize Medals, Liverpool International Exhibitioa, 1886, and 

Photographic Exhibition, 1888. 


Full-Sized LAKTERNSlromliuuiEi to SIXTY POUNDS. 

Manufacturers of SLIDES to the Wholesale 
London Houses, &c. 


ARCHER Ei SONS, Lantern Specialists, 

Brin's Oxygen Gas, compressed in Cylinders. 


Magic Lantern Slide and Dissolving 1 View Artist, Photographer 

and Manufacturer of all kinds of Lantern Slides. 
Designer and Producer of Mottoes, Curtains, Comics ; " The Seasons," " Funny 
Faces with Moving Eyes ; " Skipping, Slipping, Photographic Effect Sets, and 
Mechanical Slides. Also the celebrated set " The Village Blacksmith." 

Transparencies produced from Drawings, Engravings, Ac., aud Customers' Own 
> etfatives. Slide Colouring for the Trade and Private Customers. Special 
Lecture Set* prepared, and Original Designs made. Hand-painted Slides to 
order. Slides by all the best producers, and all the Latest Novelties in Stock. 
Slide Carriers, Frames, &c. 


23a, Clarendon Rd. Croydon, Surrey, near London. 


30 Interesting Sets, with Descriptive Lectures. 


Slides made to order from any view in our General Catalogue. Over 10,000 subjects 
to select from in England, Scotland, Wales, & Norway. Catalogues, post free, 6d. 


Pbotograplrc Publishers, 152 and 154, Perth Road, 




New Enlarging Apparatus. 


THIS APPAKATUS is designed specially for Amateurs, who, ot having 
attempted enlarging before, require an Apparatus that is not only simple and 
easy to work, but effective in results. The L. S. Co. feel sure that this 
Apparatus will meet the above requirements better than any that have been pre- 
viously designed, not only for completeness but for its extreme utility. 

PRICES complete, with three-wick lamp, for giving a most brilliant and effec- 
tive light, with tin case, encased in mahogany body with a sliding-camera front, 
for adjusting to various sizes, fitted with one of the London Stereoscopic Company's 
best portrait lenses, with rack and pinion adjustment. The whole of the above is 
fitted into a box, with dishes, enlarging paper, chemicals of all sorts that are 
necessary, together with the various et cat era ; the lantern is fitted with a splendid 
5-in compound condenser. The above is the most complete and perfect Enlarging 
Apparatus ever designed, and will give perfect satisfaction to our numerous amateur 
and professional patrons. 

Small size (5-inch condenser), price complete .10. 10s. 

Larger size, for enlarging from half-plate negatives 

(7-inch condenser), price complete .15. 15s. 

A FREE DEMONSTRATION given to Purchasers of the above 
Enlarging Apparatus at any time by appointment, at 


And 54, CHEAPSIDE, B.C. 


To Lecturers and Others using the Oxy-Hydric Light. 

BRIN'S OXYGEN CO, Ltd, sappi, 


And also Hydrogen, or Coal Gas, compressed in 
portable vessels, at the following low prices: 


Tested to 3,000 Ib. per square inch, and fitted with Brin's Oxygen 
Company's Patent Value. 

in feet. 

in Inches. 

over all in 

Weight in 

Price or 
Deposit on 

Kent per 
week after 
the first 14 

Prices of Oxy- 
gen or Hydro- 
gen per cubic 














In quantities of 
20 ft. or less, 

Over 20 ft. and 
up to 60 ft. 

In quantities of 
more than 
60 it. 2d. 

FITTINGS : Nipple and Union, 2s. 3d. ; Key, 2s. 9d. 

TERMS: Net, cash with order. 

Deposits : Customers not wishing to purchase cylinders, must 
send with their order an amount equal to the price of cylinder and 
fittings, as a deposit ; and on all cylinders not returned within 14 
days, rent will be charged as specified above. 




(Works, 69, Horseferry Koad, Westminster, S.W.) 




la the Best Photographic Plate made for the production of 
Transparencies and Slides for the Optical Lantern. 

The effects produced on these plates cannot be surpassed for 
delicacy and brilliancy. 

The Developing Formula is simple, handy, and cleanly, and 
will meet with special welcome from Amateurs. 

Instructions accompany each Box. 

SIZE 3jx3J 4|x3| 5x4 6x3J 6x4| 6|x4f 7|x4 7x5 

Prdoz 1/4 1/9 2/3 2/6 3/- 3/6 4/- 4/tt 

SIZE 7^x5 8x5 8^x6^ 9x7 10x8 11x9 12x10 15x18 

Per doz 5/- 5/6 6/6 9/- 12/- 14/6 16/- 281- 

J. HASWELL, Esq., Sunderland. 

"'The Amateur Photographer' Silver Medal has been 
awarded to me for the transparencies which I exhibited. They 
were ail done with your ' Lantern ' Plate." 

B. G. WILKINSON, Esq., Streatham Hill, S.W. 

" I am pleased to tell you that, at the Liverpool Photo. Exhibition, 
1888, 1 was awarded a Silver Medal for Lantern Slides, which 
were made upon your Mawson Lantern Plates. I consider your 
plates excellent in every way." 


March, 1888. 

" The specimens of Lantern Slides treated with different developers 
are singularly fine." 


"April, 1888. 

"In our hands we have always found good results from their 
plates, and the Lantern Plate is unequalled in the market." 

MAWSON & SWAN. 33, Soho-squire, London. 
Mosley-street, Newcastle-on-Tyne. 



Messrs. D. NOAKES & SON 

Would call the special attention of Lecturers, Users, 
and Intending Purchasers of 

To the PRACTICAL SUPERIORITY of the Apparatus they Manufacture. 

The whole of the Improvements adopted by 
MESSBS. NOAKES & Sox have been suggested 
by a long practical experience, Mr. C. W. LOCXB 
and Mr. D. W. NOAKBS, two of the Principals 
of the Firm, having personally operated at 
upwards of 5,000 Exhibitions. 

MESSES. NOAKES & Sow would also call the 
attention of Lecturers and others to their Im- 
proved Method of COBBBCTING BI-UNIAL and 
TEATION of the most complicated effects can be 
secured at every and any distance from the 
screen. Special attention is also called to the 
without which no Triple is complete. 

Mr. LEWIS WEIGHT, writing in the Sritinh 
Journal of Photography, March 9th, 1888, says : 
" Another ' mistake ' exhibited was a telescopic 
front with rack and pinion to every ' draw ! ' 
Again, this is mere useless expense and unprac- 
tical ..... We do not want in a lantern any 
.mechanism that is not of distinct use, but 
Ppractical simplicity, with no more weight and 
size than are needed. Mr. Noakes showed 
how, by the ' loose jacket ' now coming into use among those houses which really 
have the largest experience, a lantern with only the single ' draw ' usual on all can 
have a * range ' of focus of seven inches between greatest and least. . . . This tap 
is a really good thing, as is the triple ' dissolver ' of Noabes. By ranging two sets 
of holes on one spindle, this tap dissolves any pair of lanterns, or puts on any 
single; and by separating the 'setting' and 'dissolving' levers this is done with 
absolute certainty and simplicity in the dark, while bye-passes can be arranged 

NOTICE. Mr. D. W. Noakes and Mr. C. W. Locke personally 
give Lessons in Operating. 

Full Particulars and Catalogues, post free, from 


Inventors, Patentees, and Makers of 

Improved Magic Lanterns, Dissolving View, Lime Light Apparatus and 
Slides, Photographic Lenses, Cameras, etc. 


TELEPHONE, 8029. HOURS, 9 to 6. 

ALL work being done on the premises, Repairs and Alterations can 

~be executed on the shortest notice. 




NEW SETS OF SLIDES.-Architecture-Lifeboat 
Services Types and Anti-types of our Lord Spanish. 
Armada English Church History Rise of Nonconformity 
Botany The Great Ice Age Food Adulteration The Bngadine 
The Riviera Berlin Rise of English Literature Tales from 
Life-Models, and 60/00 other S'ides in stock before. 

The "EUPHANERON " LANTERN, with the Four-wick 
W Lamp, 4. 4s. 

Tne "CHEAP" LANTERN, with 4-in. Condenser and 
Three-wick Lamp, 1. 15s. 


^ WOOERS *+ 

Photographic Outfits. 


4^ by 3t, complete with chemicals, &c., in case 2 15 


44 by 3$, complete with chemicals, in case 5 


6 by 4f, complete with chemicals, in case 8 12 

" A PHOTOGRAPH, AND HOW TO TAKE IT," together with 
complete list of Photographic Apparatus. Post-free One Stamp. 

E. G. WOOD, 74, Cheapside, London; and 




SfflFT & 

Manufacturing Opticians 







No. 1 for Portraits 61 by 4| .... 1515 

2 81 61 .... 24 6 

,,3 10 8 .... 35 4 

4 18 16 .... 38 5 

5 22 18 .... 49 12 


No. 1 for Cabinets, 14 ft. distance.. 11 14 

2 .. 18 ft. .. 15 15 

3 ,. 20 ft 17 11 


No. 1 for Cards .. 14 ft. distance.. 5 10 
,,2 .. 16 ft. ..660 

3 .. 19 ft. .. 10 3 


Invaluable for Photographing Children. 

No. 1. 41 in. focus, diani. 2J in. .. 12 3 

,. 2,6 in. focus, diam. 31 in. .. 22 10 








Dia. of 


in Rigid 





10 8 
12 10 
15 12 
18 16 
22 18 
25 21 
28 24 

8} 6| 
10 8 
12 10 
15 12 
18 It 
22 18 
25 20 

2 in. 



20 ',', 


. s. 
8 2 
11 5 
14 17 
22 10 
40 10 
49 10 


Working Aperture, U.S. No. 4, F/8. 


Size of 

Dia. of 




5 by 4 

1| in. 

51 in. 

2 19 

71 41 
81 61 

it " 

7 ., 

4 1 

10 , 8 



4 19 

12 , 10 




15 , 12 



7 19 


18 , 16 

3 , 




22 , 20 


12 12 


25 ,21 



17 2 







Cove r- 







3 by 3 

4 by 3 

5 by 4 

3 in. 

2 14 


4 3 

5 , 4 

71., 41 


2 18 6 


5 4 

71. 4* 

8 5 




71,, 4* 

8 , 5" 

81,, 6) 


3 12 


8 5 

81, 61 



4 10 


8J 61 

9 , 7 

10 8 


5 << 


9 7 

10 , 8 

12 10 




10 8 

12 , 10 

13 11 




12 10 

13 11 

15 ,, 12 




13 11 

15 12 

18 ,, 16 




15 12 

18 16 

22 ,, 18 


10 16 


18 16 

22 20 

25 21 


13 10 




Size of 

Size of 

Dia. of 



Price in 


4 by 3 




41 in. 

3 12 

5,, 4 

41 by31 


3 16 

6 6 

5 4 




4 14 6 

8 5 

71,. 4i 






8 5 



5 17 6 




Sfc ! 




6 15 
7 12 



10, 8 






11 . 

13 , 




10 7 



15 , 




16 13 



18 , 




22 10 



J-2 . 






24 i25 , 


41 .. 38 



Giving 100 of angle for Photographing 

Largest Dia. of 


of Plate. 








71 by 41 
8* 61 
12 10 
15 12 

It ., 

2 ',', 


4 in. 

81 ! 

4 1 
4 19 
9 9 


18 16 



13 , 

12 12 


22 ,,20 






25 ,,21 

3| ., i!7 

19 , 


Iris Diaphragm fitted to above Lenses. For Price, &c., send for List. 

University Optical Works, 81, Tottenham Ct, IL1 








Optical * Lanterns 

every descrittion and of the highest 
quality, as supplied to the Science and 
Art Department and all the principal Uni- 
versities at home and abroad. 

Slides of Every Subject. 
Lantern Slides 

Of the Best Quality only, made from 

customers' Negatives or Sketches at 

low prices. 


3 in. to 15 in. 



Wright & Newton's Patent Projecting Microscopes 

FOB ELECTBIC AND LIME LIGHT. See page 243 of this Book. 

SOLE MAKEBS rj Q I M f* I CT Q I CTT See page 55 of 
OF nK I IM VJ Lt O J t I , this Book. 



See page 6 of this Sook. 
Largely used by Professional Photographers and the Trade for Enlarging purposes. 

Newton's Patent Microscopic Attachment, 

To fit on any Lantern. See page 242 of this Book. 
Full Illustrated Catalogue of Lanterns, Slides, &c., ad. 


l\l QWTnn Or I n AND H ' K H - THE ^ BINCE OF WALES. 

I V II W I XI I 1 1 1 Makers of Lanterns & Slides to the Admiralty, 

ll U If lUJI Ok. U U the War Department, the Science and Art De- 

3 partment, and the principal Scientific Societies, 









Lantern Slides 





Works : Newcastle and Gateshead. 

Optical Lantern * Slides 

Occupy the most prominent position in the market. 


Negatives Purchased. Slides made from Amateurs' Negatives. 

& soisr, 


SCIOPTICON. Optical Lantern. 

Oil Lamp, giving more, whiter, and steadier light than any 
other, fitted with simple and perfect Slide Changer ............ 4 10 

SCIOPTICON. Lantern Slides. 

Unapproaf hable f or tone, brilliance, and transparence, per doz. 10 
List and Sample sent free to any part of the world for Is. 6d. 

SCIOPTICON. Camera&Lenses for Lantern Slides. 

Indispensable for artistic work. Range of camera and lenses, 
3 to 12 inches ; 5 lenses, making 4 rectilinear ; 4 double 
dark slides ; packed in handsome case ; rigid stand, the whole 
i-plate outfit weighing under 7lb., price ........................... 10 10 

GEORGE SMITH, 26, Colebrooke Eow, London, N. 

(Trading as the S-IOPTICOtf COMPANY.) 



New Enlarging Lantern 

great efficiency with extreme portability, 
and gives the highest satisfaction for the quality 
^-* of its results and the ease and facility with which 
it may be manipulated. It is without doubt the best 
enlarging lantern in the market. 

SPECIFICATION. Copper body; first quality con- 
denser; improved bellows front; cabinet portrait lens; 
patent circular wick to lamp; carriers for small-sized 

Prices, Particulars, &c., on Application. 

ticulars and prices of every article required in the practice of 
photography, with notes on development and other operations, 
post free, SIXPENCE. 

TRTratten & "Wain-Wright, 

Sole Manufacturers of the "LONDON" DRY PLATES, 


-w^o. ^ 




The Melsenfrach Improved -Process of Engraving Paintings, 
The Meisenbach Improved Processor Engraving Pencil Drawings 
The Meisenbach Improved Process of Engraving Photographs, 
The Meisenbach Improved Process of Engraving Wash Drawings 


The MEISENBACH BLOCKS are now used for the 

Illustration of all the leading Art Publications 

and Illustrated Papers of the day. 

Specimens and Full Particulars post-free on application to THE 



Qarion j _ Jghoto -_ UPJy_ jgtarehouse. 

COW.A.:N 'a 

For Lantern Transparencies. 


These Plates have been in the market for some years, and give great satisfaction. 

They are novr sent out m grooved boxes, thus preventing any risk of scratchiug or 

markiug of the Plates by the Tissue Paper. 

Messrs. BOBIHSON & THOMPSON, of Liverpool, write of these Plates on 

October 2, 1888, 

' ' The Cowan's Transparency Piates lately received in grooved boxes were 
simply perfection. There was not a flaw on them of any kind." 


Per Doz. 

Per Doz. 

3 x 3i 


8* x 6|... . 


4i x 3i 

2 6 

9 x 7 ... . 




10 x 8 ... . 

14 6 

6j x 4 

5 6 

12 x 10... . 


71 x 5 

7 6 

13 x 8 











Per D 
31 2 








x fii , 10 
x 7 . 12 




4 ... 




8 ... 








Fitted with a Voigtlender's Rapid Euryscope Lens, which, when not in use, racks 
into ihe body of the Camera. The Lens ia of the best construction to secure sharp 
definition, so necessary in Lantern Slides, which, when thrown on the screen, if the 
Negative be not sharp, will enlarge all defects ; besides the quality of Lens, the 
Metal Camera itself is so compact and bandy that with 12 Slides it may be packed 
in about 8J by 6 in. Price complete with 12 Slides, Q. 10 S. 6d. 


Fitted with Compound Condensing Lenses. 8J inch, and Patent 3- wick Paraffin 
Lamp, giving a very powerful light. Price 7. 

MARION & LQ,,22&23, Soho-sq, London. 

b 2 



89, High Holborn, London, W.C. 


Specialty for Dark Room Developing 
Sinks, Lanterns, and Fittings. 



Prize Medal, Crystal Palace Exhibition, 1888. 


Combining Lightness, 
Rigidity, and all latest 
improvements, at the 
lowest possible prices. 

Complete Sets of 





Member of the Lecturers' Association, 

22, Gray's Inn Road 

(near Holborn), 

., "W.C- 

Dissolving > View > Artist 




Second-Hand and New Apparatus and Slides in 
Great Variety. Lists Free. 

Slides produced from Amateurs' or Professionals' 
own Negatives (glass or film), and supplied plain or 

LANTERNS Complete, with 4-in. Condensers, from 36s. 
SLIDES, 12s. & 15s. per doz. Coloured, 18s., 24s., & 30s. 

Always a large collection of cheap sets from 12s. per doz., coloured. 




22, Gray's Inn Road, London, W.C. 





AMATEUR * I A pop tu r nr rated 
'r\ -i 


Devoted to 
Photography and 
the kindred Aris. 


fye Jlmctfeur ^fyotogvcipfyey: is the 

Special Organ of the Amateur Photographic 
Societies of Great Britain and the Colonies. 

Jlmateur ^gp^otocjrapBer contains 
Articles upon all subjects, both Technical and 
Social, interesting to Amateur Photographers. 

B JltttClf<?ltT' ^Jp^ofocjtrcipBtMr has a special 
page devoted to Queries and Answers. 

^SBe Jlmafettr ^pBofograpl^er is the best medium for 
the Sale and Exchange of new or second-hand apparatus. 

London : Hazell, Watson, & Viney, Ld 

52, LONG ACRE, W.C. 

And through all Newsagents and Photographic Dealers. 

10s. lOd. per year, 5s. 6d. for 6 months. 



f^er fKajestg in 
to Scotland 


Publish the best and most complete series extant of 
Photographic Views of ENGLAND and SCOTLAND. 

mHEIR SB RIBS contains views of almost every note- 
worthy district in Great Britain, from Land's End to 
John o' Groats. It includes London, complete series of the 
English Cathedrals, The Thames, Oxford and Cambridge, 
Shakespeare's Country, Bristol and the West of England, the 
"Dukeries," Derbyshire and the Scenery of the Peak, Yorkshire, 
its Cathedrals and Watering Places ; and in Scotland, a complete 
set of Edinburgh, Glasgow, Aberdeen and the large Towns, the 
Scenery of the Borders, the Land of Burns, the Trossachs, the 
Firth of Clyde, the Lochs, Bens, and Glens of the Highlands and 
West Coast. Views illustrative of the Scottish Crofters, Deeside 
and Balmoral, Orkney and Shetland, &c. 

All or any of which can be had as Lantern 



Ltctnre Season, 1888-M. 




Popular & Scientific 


MR. HEPWORTH begs, to call attention to 
the following Lectures, all of which 
are lavishly illustrated by Limelight Pictures 

mostly in the form of (Dissolving Views, their 
size being only limited by the capacity of the 

Footprints of Charles Dickens. 

This new Lecture combines readings from a most popular author, with limelight 
illustrations, and represents a totally new form of Entertainment, which is sure to 
prove attractive. It is illustrated by about 100 Pictures. For details of this im- 
portant Lecture see separate circular. 

Old and New London. 

A fully illustrated account of the City as it was before the time of railways, 
contrasted with its appearance to-day. Many beautiful pictures of old buildings 
now pulled down are included in this Lecture, which also comprises instantaneous 
Photographs of modern London and its people. 

Earthquakes and Volcanoes. 

With Illustrations from nature, many of them having been taken by the Lecturer 
at the scene of disturbance. 

For Terms and Dates, address 





Photographic Apparatus for Tourists & Aiateurs. 

New Ready Sensitised Paper, Photo Mounts of first- 
class quality, and every requisite in stock. 

All Orders mailed same day as receipt of Remittance. 




The "BIJOU " Set of Lanterns and Slides, from 10s. 6d., 
complete in Box. 


In Gold, Silyer, and Steel, fitted with the best Brazilian Pebbles or Periscopie 
Lenses of the finest quality. 

Price Lists and full particulars on application. 

T. & H. DOUBLET, 11, Moorgate-st, Bank, E.G. 


Wholesale and Retail Manufacturers of 

Improved Optical, Bi-Unial& Tri-Unial Lanterns, 



New Designs in Mechanical Slides and Effects, painted by first- 
class Artists. Projecting Polariscopes and Microscopes. 

Sole Address : 178, ST. JOHN STREET ROAD, 

(Near the " Angel") LONDON, B.C. 




Prize Medal, Highest Award, Photographic Exhibition. 

fitted with High-class Objectives. 


Price 42. 

Will give from 10 to 
30 feet pictures. 

TIVES, for projecting a Picture at a very long distance without loss of light. 
Most splendid definition and results, as supplied to B. J. Maiden, Esq., Rev. 
Frank White, Colin Docwra, Esq., who pronounce them perfection. (See 
Testimonials and Opinions of the Press). 

NEW MICROSCOPE ATTACKMENT; will show Eye of Fly 16 ft. in diameter. 

or Limelight for showing solid objects, as constructed for W. Lant Carpenter, 
Esq., B.A., B.Sc., for the Victoria Hall, London, at from 80 to 100 feet from 
screen ; also Free Trade Hall, Manchester, for Prof. Forbes, with tremendous 
success, to over 5,000 working men. 


W. C. HUGHES, Brewster House, Mortimer Rd, Kingsland. 






Price from 2. lOs. 

PATENT TRIPLEXICON, 4 inch double Condensers, 2. 2s., 
3 inch, 1.15s. 6d., the finest 3-wick Lantern in the world. 

See opinion of Sir Antony Brady, Dr. Croft, &c. 
EDUCATIONAL DUPLEXICON, 31 inches, 1. 7s. 6d. 



The only perfect Enlarging Lantern. No Amateur Photographer should be 
without one. Rectangular or Square Condensers exactly the shape of negative, 
therefore reduces Lantern half the size. Prices from 8. 10s. List free. 

First-class Bi-Unial, brass front, jets, dissolver, gas bags, &c., complete, only 
15. 15s. 

Semi-Automatic Self Centreing Carrier, Presto-Instantaneoua Carrier, an 

Articulosus Screen Frame Pandiscope Lantern Stretcher, marvelleous effect, 
&c. 60,OJO Slides, 300 Lectures, 50 sets of Life Model Subjects, Pantomimes, Ac., 
from Is. each. Art Gallery, Workshops, &c. JS"ew elaborately Illustrated Cata- 
logues, 300 pages, full of valuable information, 160 woodblocks, Is., postage 4d. ; 
ditto, pamphlets 4d., postage Id. Cheapest ana best, of tbe manufacturer, 

W. C. HUGHES, Patentee & Specialist, 

Breuister House, Mortimer-rd., Kingsland-rd, , London, H. 




For all those interested in the 





s. d. 

Yearly Subscription, including Home Postage ... ... 7 6 

To the Continent, Canada, United States, and Egypt ... 76 

To West Indies and South America 90 

To the East Indies, China, Ac 10 6 

To South Africa 12 

To Australia, New Zealand, &c 14 


Vols. I. and II., profusely Illustrated, are now ready, 

and can be had of the Publishers, price 8s. 6d. each, 

post free, 9s. 







Argentic-G-elatino-Bromide Process. 

The Standard Method of Producing Permanent Enlargements and 

Contact Prints, 


POSITIVE PAPER. For Enlarging and Printing direct from 
the Negative. 


1-doz. Size. 






8 x5 
Six 6| 

(2-dz.) 1/3 10 x 8 
1/3 12|xl<H 
1/9 15* x 124 
2/3 18 x!5 










In Rolls of 20 ft., 17 in. wide, 12s. ; 25 in. wide, 17s. 6d. ; and 39 in. wide, 21s. The 

Positive Paper can also be had with a rough surface, same price, but in all cases, 

unless rough is specially ordered, smooth is aent. 

NOTE The Argentic-Gelatino-Bromide Papers are sent post 
free. SAMPLE SHEET, 23xl7i Is. 6d. 

NOTE. By this process beautiful enlargements may be 
made with the ordinary optical lantern. 



From good small Negatives, are full of Delicacy and Vigour and 

Equal to a Fine Engraving. 


An Enlargement from a good negative is A PICTURE AND A WORK OF AKT, and 
is far better than a photo- scrap. 





PARIS 29, BOULEVARD DES ITALIKNS. Telegrams - Argentic, Richmond, Surrey. 



For Uiitera Slide Pictnres. sto 3! x 3S in. 

Exceedingly portable, when closed for the pocket, measuring 

4 X 4 X 1-| in., is the Lightest and Smallest Camera made for the size of picture. 
C^- The Camera is made in polished Ebonite, and is quite unique in its appearance. -^ 

With this Camera held in the hand, Instantaneous Pictures can 
be taken in bright weather, of which many examples have been 
done, as Streets in the City, with the regular traffic ; views of Ship- 
ping, &c., on the river ; open view from Kailway Carriage Window 
when travelling at a rapid rate ; Country Scenes of Cattle Feeding, 
&c. &c. It can, as well, be used with a stand for longer exposures. 

The price of the Camera, with one Double Dark Slide, Lens, and 
Shutter complete, is 3. IDs. Extra Dark Slides, 7s. 6d. each. 
Portable Stand, which can be used as a Walking Stick, the three 
legs fitting into one tube, 17s. 6d. 

Special Plates, most rapid procurable, to use with Shutter Ex- 
posure, Is. 6d. per dozen ; ordinary rapidity, Is. 3d. per dozen. 



Makers of Dry Plates, Cameras and Photographic Requisites 

Mayfield's Universal Developer, in one Bottle, does not stain the 

fingers, and can be used with any mafce of plates. A boon to any 

Amatenr. In bottles, 2s. Particulars on application. 






Scientific Accessories for use with Lanterns. 

Photographic Lantern Views from all parts of the World. 


from .7. 10s. 



from 15. 15s. 



Of highest quality, for 

burning Paraffin Oil, from 

2. 10s. 


1 4 GOLD & other 

Medals at various 

Exhibitions for 
Excellence of In- 

>t J/luxfrafed Catalogue 
qfLuntertts and lit of 
Accessories and Slit1e 
tent pr>st free to ai<y 
part of the world on 

No. 1031. 



Steam Factory 9, 10, 11, Fulwood's Bents, Holborn. 

RETURN TO the circulation desk ot any 
University of California Library 

or to the 

JO Blc| g- 4 n ' Richmond Field Station 
LQ} University of California 

Richmond, CA 94804-4698 


2-month loans may be renewed by calling 
j (510)642-6753 

1-year loans may be recharged by bringing 
books to NRLF 

Renewals and recharges may be made 4 
days prior to due date. 


APR 5 1997 MAR 2 4 2003 


JUL i i 1330 


A - nii 9M996 

FORM NO. DD6A,^m / 4^77