There are a number of topics of interest that are related to Argand, sinumbra, and solar lamps. You can read more about each by clicking on any of the underlined topics below. We think that you will find the information to be interesting, educational, and at times a bit humorous. If you should have anything to add - or for that matter if you should take issue with any of the information - please be sure to get in touch. I would enjoy the opportunity to visit with you. Check back from time-to-time as this section will be updated as new information becomes available.
Up until as recently as the late eighteenth century, lighting technology advanced very slowly since the time when man first learned to control fire for heating, cooking, and illumination. During the 1780s, a Frenchman, Ami Argand, made a startling discovery. He found that by using a circular, hollow wick rather than the conventional solid wick, the flame would burn much brighter because the surface area of the wick was greatly increased (air for combustion was drawn up through the center of the wick as well as over the outer surface). Lamps employing this latest technology were so successful that they sold by the thousands in Europe, England, and the United States. It did not take long for others to copy and slightly modify Argands lamps. One modification, the sinumbra lamp, was developed in France around 1820. These lamps used the standard Argand burner and were primarily designed to reduce the shadow that was typically cast by the font of earlier Argand lamps. Both lamps burned high-grade oils such as sperm whale oil or colza oil. Another very popular modification that was developed around 1836 was commonly known as a solar lamp. These lamps utilized the typical Argand central draft burner with the addition of a deflector cap. This resulted in a brighter flame and the lamp's ability to burn lard and lower grades of whale oil.
All of the lamps shown in this gallery are made from brass, bronze, and tinplate. The various brass and bronze parts are machined, cast, and spun using molds and chucks that have been made and copied from parts of old lamps. Lamps are electrified using both halogen and standard incandescent bulbs; halogen bulbs are generally used on lamps that have a chimney but no shade. It is important to note that careful attention is given to the actual physical placement of the bulb making it virtually impossible to distinguish electrified lamps from oil-burning lamps. Bulb wattage can be matched to the intended use of the lamp and this versatility makes these lamps perfectly suited to be used to illuminate living areas in homes and display areas in museums. Some of the chandeliers and other lamps have a small on-off/dimmer switch discreetly mounted inside the lamp. This innovative design makes it possible to operate the lamp in situations where a remote switch would be inconvenient to use or very difficult to install.
Lamps have finishes that are appropriate for each individual lamp's design and style. Paint colors currently available are opaque Prussian blue, Hunter green, red, mustard yellow, and black. Striping is done in red, black, and yellow. Stenciled designs are available on the Argand Side Lamp; lamps made using brass are now available with a period acid-blackened and lacquered finish - period gold finishes will be available soon.
A program has been implemented that will make mock-up models of the various chandeliers, sconces, and table lamps available to those of you who are interested in purchasing a lamp but are uncertain if its size and level of illumination will be appropriate for your particular situation. Models of the Argand 4-burner Chandelier and Argand Side Lamp are currently available through this program. Please inquire regarding details and availability.
As always, your comments, questions, and orders are most welcome.
Members of a Philadelphia area historical society recently purchased a new reproduction Argand three-burner chandelier for a house that they were restoring. The chandeliers painted finish looked new as it would have appeared if it had been purchased new in the 1840s. Some of the members thought that the finish was fine while others felt that a worn or used look would have been more appropriate.
Who was right? Can we say with any degree of certainty? I think that it is important for both societies and individuals to develop a grand plan before starting work on a restoration project. What is the time period to which the property is being restored? Would the house and furnishings have been relatively new? What level of care might the house and furnishings have received from their owners at the time? I think that only after you have addressed these questions as well as some less tangible factors that are explored below to the best of your ability, will you be able to come to a conclusion as to who might be right.
In the case of the chandelier, consider that fixtures of this type were quite expensive in the early nineteenth century and that generally only affluent people or well endowed institutions could afford them. There is little doubt that a decision to make a purchase of such magnitude would have been given careful consideration. The chandelier would not only produce more light than any previous lighting fixture, but it would also serve as a reminder to those who saw it that the owner enjoyed an elevated station in society.
I do not think that people today are so very different from people of the 1800s and that we share many of the same emotions, likes, and dislikes. In this day and age, we travel by car or plane while in the 1800s travel was by foot, horseback, or carriage. Generally speaking, when someone purchases a new automobile, he or she tends to give it a high level of care regular washing and waxing, and servicing of the motor. He or she is proud of the purchase and strives to keep it in tip-top shape - not only for their own personal satisfaction, but also perhaps because it makes a statement to others about their persona. Why would we expect our forbearers to behave any differently? I am sure that many kept their horses, harnesses, and carriages in excellent condition the evenly matched and spirited horses looking sleek and trim, the harness leather supple with brass fittings highly polished, and the carriage immaculate and shining like a drill sergeants boots. Along this same vein, consider that today people keep their sterling silver highly polished and prominently displayed. In yesteryear they would surely have done the same. Even people of lesser means hired women who traveled from house to house to polish the owners tinware, commonly referred to as poor mans silver.
Would we expect a chandelier to be cared for in any other way? It would not have been hung and then forgotten, for regular use would have required daily servicing. Wicks needed trimming and changing, the fuel reservoir replenishing, and the chimneys and shades cleaning - all on a regular basis. It is hard to imagine that the chandelier itself would not have been carefully wiped down as well.
If a historical society seeks to restore their holdings so that they accurately represent how they appeared in a certain period, they should do so as carefully as possible. Their efforts will educate future generations about the way things really were in the past, not as we imagine they might have been. Sloppy, inaccurate research can have far-reaching negative effects.
Individual home owners do not necessarily have to adhere to the same standards as a historical society. We are all free to just plain enjoy antiques and to fall in love with a chandelier that looks every bit of its 200 years of age. Few of us are out to educate the world or to accurately represent a certain period within our homes; we ought to do what pleases us.
Antique Argand and solar chandeliers can easily cost sums that run five or more figures. If you cannot find or afford an antique fixture that suits your needs, an accurate reproduction fixture just might. And that often leads to making a decision: do you purchase a chandelier that has been artificially antiqued or one that represents how the fixture would have looked as it came out of a shop in the 1800s?
Which do you chose? When I compiled my first catalog twelve years ago, I included a Forward that addressed this question:
I am sure that the old cream jug could tell quite a story if it could relate all the history that was mirrored in its once-bright surface. Perhaps it could tell of its purchase by a young newlywed couple, trips to the creamery at a neighboring farm, babies growing into young adults and eventually its new residence in the home of one of their married children. The jug had been passed on from generation to generation to become a family heirloom.
My old cream jug marked the beginning of my appreciation and reverence for period tinware and is, with little doubt, responsible for my decision to offer my tinware with a bright, shiny surface finish, the same as that of tinware our forefathers purchased many years ago. Finished this way, mirroring your familys personal history, over time and with use your purchase will become a family heirloom acquiring its own dents, scratches, and patina to become an authentic antique in its own right.
It is my sincere hope and desire that you will enjoy and use your purchase so that it can become to you and future generations what todays antiques were to our forefathers and are to us today.
Twelve years later I still feel the same way. An artificially antiqued reproduction will always be just that and no more. On the other hand, a finely crafted reproduction will one day become an authentic antique in its own right. Please do not misunderstand my intent. I would not presume to think that you should agree with me or that my thoughts are correct in all circumstances. There really is no right or wrong answer and each individual is blessed with the freedom to make his or her own choice.
Seale, William Recreating the Historic House Interior, copyright 1979, The American Association for State and Local History, 1400 Eighth Avenue, South, Nashville, Tennessee 37203, ISBN 0-910050-32-5
The degree of difficulty in making a reproduction is in direct proportion to the complexity of the piece to be reproduced. One of the first questions to consider when deciding whether or not to reproduce a particular lighting fixture is "Will it sell?" - but the very first question that I ask myself is "Do I like it?" and if the answer is yes then I survey a group of friends to get their reactions. While this is not a terribly sophisticated market survey it has proven to be quite successful. In the case of this 4-burner chandelier, these questions were easy to answer and I did not consider conducting a market survey - how could anyone not like it?
The lamp must be studied closely keeping several key things in mind: first, how well does the fixture lend itself to being electrified and second, how practical will it be to make it an exact reproduction. Electrification issues revolve mainly around how well the wires can be hidden from view, so all parts of the fixture are examined from this perspective. In regard to the practicality of making this chandelier an exact reproduction, one main issue was immediately apparent. The canopy and the hooks at the top and bottom of the support rods were rather heavily carved and these castings were not of the highest quality. Even if it were possible to get permission from the owner of the chandelier to make molds from these parts it was likely that the resulting castings would not pass inspection because successive generations of molds and castings loose detail and dimension. So making an exact reproduction was out of the question unless an artisan was hired to carve the required pieces: it was determined that the project would not likely bear this cost and most importantly that substitute designs would easily blend in with the style and design of the chandelier.
Photographs and precise measurements were taken of all of the parts of the fixture. After this was done, everything was double checked and an inventory taken to be sure that all parts and all parts of each part had been photographed, sketched, and measured; it can be expensive and sometimes impossible to re-visit a fixture to obtain an overlooked detail or measurement.
* * *
In the case of this chandelier it is quite easy to hide the wires and where they are exposed the color of the insulation will blend in well with the color of that part of the lamp with which they come in contact. The photograph to the left shows a cut-away section of a hook with a short piece of the brass tubing. You will note that the steel rod that holds the assembly together is screwed into a hole that is offset in the end of the hook - this offset was necessary to make adequate room for the wire within the tubing. The photograph to the right shows the wires as they exit the tubing at the top of the rods and extend up through the canopy.
New designs were developed for the hooks and canopy while taking into consideration the shapes and dimensions of the original pieces and incorporating as much of the "feel" of them as possible. The photograph to the left shows a drawing of the new canopy and the rough castings of the new parts; the photograph on the right shows the original canopy, hooks, and tubing with the steel connecting rod.
Toward the beginning of this whole process it was necessary to work up the drawings and specifications and to make the graphite template for an appropriate shade for the chandelier and to work with the glassblower to help resolve the inevitable problems that always seem to develop along the way.
Weeks were spent at the drafting table scaling and drawing all of the various parts of the chandelier. After the drawings were completed, specifications for the font were sent to the spinner so that he could start work on the chucks or forms that are required for the spinning process. A number of the parts are cast and it was necessary to send the drawings for those parts to the machinist so that one of each could be machined and used as a model for casting. When these parts were finished they were shipped to the casting house so that molds could be made and the required number of each part cast. Drawings of all parts to be machined were sent to the machinist so that he could start working on them. Once all of the required parts were received it was necessary to develop assembly procedures and make any required jigs. After the assembly was finished, the chandelier had to be disassembled and prepared for finishing. Various hangers had to be made so that the parts could be held securely while they were patinated and lacquered.
The original chandelier is pictured on the left and the reproduction on the right. From start to finish this project required more than four solid months of work and thousands of dollars in development and parts cost. Was it all worth it? The answer is a resounding "yes". Sales have been good in the three years that this chandelier has been on the market and perhaps most importantly, from a personal perspective, the sense of satisfaction and accomplishment that has resulted is indescribable.
The very design of all Argand lamps as well as all subsequent variations requires the use of a chimney or some sort of contrivance that increases the draft in the immediate vicinity of the flame. This is readily apparent when a lamp is first lit with no chimney in place - the feeble flame burns cleanly only at a very low wick setting. As soon as the chimney is placed on the lamp the wick can be adjusted so that the flame will burn cleanly and with much greater intensity.
It is rather remarkable that two very significant discoveries
were made at, or nearly at, the same time. Certainly the invention
of Argand's lamp in 1780* was a huge leap forward in the advancement
of lighting technology but the invention of the chimney was of
equal importance as it greatly enhanced the operation of this
lamp. The first chimney was not made of glass but rather of metal;
the bottom of the chimney was placed a little less than an inch
above the top of the flame. This allowed the light from the flame
to shine forth from beneath the chimney (experiments have proven
that this is indeed what actually occurs).
In the book Brandy, Balloons, & Lamps - Ami Argand, 1750-1803 on page 21 there is a plate that, based on the description of the metal chimney, shows several lighting fixtures utilizing what appear to be these same metal chimneys.¹ Flint-glass was able to withstand the sudden heat to which it was subjected by the burner and thus the efficiency of the chimney could be greatly improved since it was possible to reduce the diameter of the flint-glass chimney so that it was not much greater than the diameter of the wick.
Chimneys developed in stages. As mentioned, the first chimney
was a short metal tube. The first glass chimneys were also cylindrical
in shape but longer in length. The extra length increased the
draft which resulted in a greater flow of air past the flame;
this caused the flame to burn with greater efficiency and thus
yielded a much higher level of illumination. The last main improvement
of the chimney had to do with its shape (see the chimney at far
right in the photograph below). An exert from An Encyclopedia
of Domestic Economy printed in 1845, describes this perfectly:
"In the original construction of Argand's lamp there was an imperfection in the glass chimney, which has been removed by subsequent improvements. The glass was at first made simply cylindrical, and then the air within rose quite vertically between it and the flame, striking upon [the flame] imperfectly; on which account the lamps could burn only the best oil. But by a French alteration of the shape of the glass, made some years ago, the lamp burns with a clearer light. Instead of being of equal width throughout, [the chimney] is contracted at the level of the flame, by which the current of ascending air is made to turn out of its course when it arrives at this shoulder, and is propelled [inward] against the top of the flame just where the smoke is beginning to part, which, in consequence, is destroyed almost entirely."²
Shades, or globes, served a dual purpose but I believe
that the original intent was likely to have been to improve function
rather than style. Shades were made of various materials other
than glass; references in period publications are made to shades
constructed of metal, paper and cloth: "To reflect the light
down, a skeleton of wire, such as is used for bonnets, was raised
over them in a hemispherical form, and on that was fixed thin
silk, which being partly transparent, had a very pretty effect."³
In this quote " ..the form of the ground glass shade assists the dispersion of the rays of light [see figure 128] .."³ 'ground' refers to 'frosted'. Many period paintings show people reading while seated at a table; the source of illumination is often a lamp with a 'ground glass shade'. Imagine the discomfort to the eyes while reading if a lamp had no shade at all or if the shade, being fancy in style, was heavily cut and polished. In both instances the reader would find the bright rays of light to be most offensive.
The scope of this reference list is rather specific and limited to information regarding Argand, solar, and sinumbra lighting fixtures as well as related topics such as (but not limited to) wicks and fuels, chimneys and shades, finishes, ceiling hooks and rods and mechanisms used to raise and lower chandeliers, and manufacturers. Your contributions to this list will be welcome the greater the participation, the more valuable this reference tool will become. If you are familiar with any books or magazine articles that you would like to recommend, please forward the information to me. If specific pages of a book or magazine are pertinent, please be sure to list them. Also, it would be helpful if you would include a brief description or review of the material. Much can be learned from period paintings and advertisements that picture Argand, solar, and sinumbra lighting fixtures and we would appreciate any references to these as well.
Seale, William Recreating the Historic House Interior, copyright 1979, The American Association for State and Local History, 1400 Eighth Avenue, South, Nashville, Tennessee 37203, ISBN 0-910050-32-5
Gowitt, Gerald T. 19th Century Elegant Lighting, copyright 2002, published by Schiffer Publishing Ltd., 4880 Lower Valley Road, Atglen, PA 19310 610-593-1777, ISBN: 0-7643-1514-5
Wolfe, John J. Brandy, Balloons, and Lamps, copyright 1999 by the Board of Trustees, Southern University Press
Chinnici, Curt R. The Manufacture of Argand Lamps in Philadelphia, The Magazine Antiques, February 2002, page 62
Carpentier, Donald G. and Sprigg, June Like the Sun, Like the Stars Argand Lamps, Early American Life, June 1995, page 56
Plescia, Vincent D. Successful Innovations in Domestic Oil Lighting, 1784-1859, The Magazine Antiques, December 2005, page 92
Cooke, Lawrence S. Lighting in America - From Colonial Rushlights to Victorian Chandeliers, copyright 1975, published by The Main Street Press, 381 Park Avenue South, New York City, NY 10016, ISBN 0-87663-253-3
Country House Lighting, Temple Newsam Country House Studies Number 4, copyright by Leeds City Art Galleries and Jessica Rutherford, ISBN 0-901981-51-6
Bourne, Jonathan and Vanessa Brett, Lighting in the Domestic Interior - Renaissance to Art Nouveau, copyright 1991, published for Sotheby's Publications by Philip Wilson Publishers Limited, 26 Litchfield Street, London WC2H9NJ, ISBN 0-85667-397-8
Dillon, Maureen Artificial Sunshine, copyright 2002 Maureen Dillon, National Trust Enterprises Ltd., 36 Queen Anne's Gate, London SW1H 9AS, ISBN 0-7078-0288-1
Webster, Thomas An Encyclopedia of Domestic Economy, published in 1845, Harper & Brothers, No. 82 Cliff Street
History of Lamps and Lighting, the Rushlight Archives: 1934-2006, copyright 2007, published by the Rushlight Club, Dan Mattausch Project Editor.
Early Argand lamp manufacturers had to concern themselves with a wide range of crafts. These included tinsmithing, machining, spinning, casting, and finishing. And since the design of the Argand, sinumbra, and solar lamps requires chimneys and or shades for proper function, manufacturers had to find sources for the glassware as well. So, it was necessary for manufactures of the period to either hire a work force that was comprised of artisans who represented the various necessary crafts or to out-source the work that they could not do, or that was found impractical to do, themselves.
What was true in the 1800's is still true today. While JP-Tinsmith has expanded its in-house 'manufacturing' capabilities, the work of certain artisans is out-sourced. From the onset, it was obvious that in order to get this business off the ground the services of a highly skilled and dependable glassblower would be required. Such a person, whose business is located in New Hampshire, was found purely by accident. He is a true craftsman in all senses of the word, dependable, reliable, and has been a most valuable asset to the business. Spinning and casting work is out-sourced as well and once again we have been most fortunate to have found artisans that are tops in their respective fields. They, too, have been a pleasure to deal with and have supplied spun and cast parts that are consistently of the highest quality.
Over time I have become aware of the fact that many people are curious about these various crafts and so this section of the site has been developed to give a brief pictorial introduction to the crafts mentioned above. Purists might complain that modern equipment that is used today was not available in the early 1800's. While that is true, keep in mind that the basic design and tasks preformed by the tools and machines that were used in the period have not changed drastically, if at all, to this day. Like all artisans throughout time, craftsmen in the 18th and 19th centuries took advantage off new technology as it became available. For example, 19th century tinsmiths took advantage of and used newly invented rotary machines that enabled them to make tinware at a much faster rate than 18th century tinsmiths who had no such machines with which to work. It was essential for their survival that they take advantage of new technology so that they could remain competitive. This simple economic principle is no different today than it has been throughout the ages.
Here at JP-Tinsmith our selection of tools spans a period
of time from the early 1800's to the late 1900's. The craft of
tinsmithing changed quite a bit in the late 1800's and over time
tinsmiths turned to roofing and heating, air conditioning, and
ventilation duct work. Because the time period of the tinsmithing
work that is done here in the shop is that which extends to just
past the first half of the 19th century, many of our tinsmithing
tools date back to that same period. The ages of our machining
tools are a different story as they date from the middle 1930's
to the late 1900's. And while this machinery may seem to be fairly
advanced when compared to that used in the early 1800's, by today's
standards it is considered to be very much out-dated and obsolete
because CNC (computer numerically controlled) technology has
since been applied to the machine tool industry.
The basic equipment used by a machinist is the lathe and milling machine. Using both of these machines, a skilled craftsman can make a wide variety of objects. The photographs below show a lathe, a milling machine, a gusset and an Argand chimney/shade holder, and the tooling used and steps taken to machine these parts.
First let's identify the various parts of the lathe: A is the gearbox, B is the headstock, C is the chuck, D is the tool post, E is the tailstock, and F is the carriage. The lathe pictured in this photograph is a South Bend Model C that was made in 1937. It was the most basic model available but by the addition of the gearbox and a different carriage, it has been converted to a Model A which provides faster gear ratio changes and powered cross feed (in-out motion) of the tool post. The headstock is mounted and fixed in one place. A rear mounted motor drives the shaft in the headstock by means of a flat leather belt. The purpose of the chuck, which is mounted on the revolving shaft, is to hold the work piece that is to be machined. The tool post holds the various cutting tools that are used to shape the work piece. The tailstock is used to hold and support the opposite end of the work piece so that it will rotate true and not wobble; this is not needed when the work piece is short in length. Unlike the headstock, the tailstock is not stationary and can be slide back and forth along the length of the bed H. The tailstock is also used to hold some tooling such as a drill bit that would be used to drill a hole through the center of the work piece. The gearbox allows for different speed settings of the long screw G that runs the length of the lathe and through the carriage - through gearing within the carriage this screw moves the carriage back and forth and the tool post in and out. The tool post is mounted on the carriage and the key to the operation of the lathe is that the cutting tool that is mounted on the tool post can be moved from one end of the lathe to the other and also in an inward and outward direction.. These motions can be controlled to within one one-thousandth of an inch and this high degree of accuracy allows a machinist to machine an amazing array of objects that are uniform in shape and size.
The milling machine is pictured in the photograph above, left. It is a Prazi II Apollo Series high precision German made machine that was purchased in 1996. It differs from the lathe in that the work is held stationary in a holder mounted on the table I and the cutting tool, held by the spindle C, rotates. Material is removed by moving the work piece past the revolving cutting tool; the table which is moved either from left to right by turning the hand wheel G or in and out by turning the hand wheel H. A is a rotary index table and B is a chuck. The work piece is held in the chuck and can be rotated for certain milling operations by turning the hand wheel on the rotary index table. The milling head, D, can be raised or lowered by turning the hand wheel E. F is a digital readout or DRO. This is an electrical device that is connected to sensors that are attached to the three motions (left to right, in and out, up and down) of the milling machine. Motion in any of these directions is registered on the screen of the DRO and allows for machining accuracy to within 5 ten-thousands of an inch. As with the lathe, the movement of the various parts of the milling machine will allow the operator to machine a wide variety of parts.
The photograph above on the right pictures a gusset and a chimney/shade holder. The machines, tools, and processes used to make these two pieces are shown below.
Both the lathe and the mill are used to make the gusset. The first operation is done using the mill (above, left) in which the curved part of the gusset that mates with the vertical burner tube must be machined . It is critical that the curvature of the gusset B perfectly matches the curvature of the burner tube. Two pieces of solid round brass rod are held in a special jig that is secured to the mill table and in this way two pieces can be machined at the same time. The cutting tool is held in an adjustable boring head A - as the tool spins it is lowered down through the work pieces so that it will make a cut the full depth of the work in much the same fashion as a hole is drilled. Because it is impossible to bore the hole to the finished diameter in one pass, this must be done in small steps by adjusting the boring head so that the cutting tool makes a cut with a slightly larger diameter with each successive pass.
In the second operation (above, right) the work piece is mounted in a chuck on the lathe and a hole is being milled or drilled through the center using a cutting tool held in a chuck in the tailstock.. In this operation, the gusset rotates and the cutting tool remains stationary.
Once the hole is drilled in the gusset it is necessary to hold the gusset so that the outside of it can be machined to look like the finished gusset in the photograph. This is done by using what is called an expanding collet (above, left). An expanding collet is a work holder that is cylindrical in shape. The end is slit in six places and the diameter is just barely smaller than the diameter of the hole in the gusset. The head of screw B is tapered so that when it is screwed in, the taper on the screw forces the six segments A in an outward direction. So, when the gusset is slipped on to the end of the expandable collet and the screw is tightened, the six segments expand outwards and grip the gusset with a considerable amount of force. The gusset is now held securely so that the outer surface can be shaped.
A radius cutting tool (above, right) is used to shape the surface of the gusset. A swinging motion of part A of the radius cutting tool rotates the cutting tool around the gusset in a horizontal plane and thereby machines the curved outer surface.
This is the disc shaped part of the chimney/holder assembly upon which the chimney and shade rest. The chimney rests on the inner walled surface and the fitter of the shade rests on the surface between the two walls. The slots in the chimney section allow for the free passage of air that is needed for complete combustion of the oil and the slots in the outer ring allow for passage of air that helps to keep the shade relatively cool.
The first operations are preformed on the lathe. In the photo left, above a smaller center hole has already been bored to the appropriate diameter so that the holder can fit down over the burner tube. The large recessed area that has just been bored with a tool called a boring bar is the area in which the chimney will rest.
In the photo above, right the area that supports the shade is being machined. This photo shows all of the lathe work that is necessary to shape the contours needed to hold the chimney and shade.
A tool called a knurler A is used to knurl the surface of the outer edge of the holder. Since the chimney/shade holder is rotated to raise and lower the wick, the knurled edge helps prevent the fingers from slipping while grasping and turning the holder. By advancing the tool post toward the back of the lathe, a considerable amount of pressure is exerted on the knurling wheel as it comes in contact with the outer edge of the chimney/shade holder; this causes the knurl to imprint its striated lines B on to the part. The lathe work is now completed and the next operation, not pictured, is to cut off the finished part from the long brass piece held by the chuck; it is cut off just to the left of the knurled area.
The last photo shows the holder held by the chuck on the rotary index table. A cutter called an end mill is used to cut the two rings of slots. The rotary index table is graduated in degrees, minutes, and seconds and this allows for very precise location of the beginning and ending points for milling each slot. To cut a slot, the table is rotated to the starting point, the spinning end mill is lowered into the work and the table is then rotated to the end point of the slot where the end mill is raised out of the work; the process is repeated until all of the slots have been milled.
Not shown is the last step which requires filing the 48
corners of the 12 slots. While this is not necessary for the
function of the part, it must be done because the corners on
all of the period holders that I have seen have been squared.
It is interesting to note that the corners on at least some of
the cast solar shade holders are rounded as seen on the holder
in the above photograph.
Below follows a pictorial and written description of the glassblowing process that we use to reproduce the Argand, sinumbra, and solar shades and chimneys. Early shades were blown in molds; our shades are blown by a scientific glassblower using a glassblowing lathe. While ones first impression is that the process that we employ is very different, upon closer inspection it is realized that it is actually very similar. This process allows us to accurately and repeatedly reproduce the profile and fitter sizes of shades and chimneys.