Grantville Gazette - Volume V (37 page)

Heliographs 

In essence, the heliograph communicates coded messages in the form of light flashes. The principal advantage of the heliograph over the electrical telegraph has been that it could be used even in hostile territory, where a telegraph wire had not yet been laid, or was likely to be cut. This is not a problem with radio communications, but the number of radio sets in the USE is limited. The heliograph was used to great advantage by the British in Afghanistan and in the Boer War, and by the Americans in the Indian Wars.

The Indian tribes had countered the electrical telegraph by cutting telegraph wires and poles; the mirror telegraph was much less vulnerable to enemy action. The Apaches understood the significance of the heliographs all too well; they avoided the territory crisscrossed by the heliograph network. (Rolak).

The signalers were typically 25-30 miles apart, and could send messages over distances of 800 miles in less than four hours. (Wrixon, 435). The average speed of the system was reportedly 16 words per minute. (Holzmann). In 1894, the U.S. Army set a new heliograph distance record (183 miles).

The 1865 Mance heliograph had a tripod-mounted mirror linked to a key mechanism. The key tilted the mirror in and out of position, causing it to flash on and off. (Plum, 30). In a late nineteenth-century U.S. army design, light flashes were achieved by coupling the key to a shutter placed in front of the mirror. Some versions of the Mance heliograph had two mirrors. Just one mirror was used if the sun were in front of the sender. If the sun were behind the sender, the second mirror could be positioned to reflect the sunlight onto the one facing the recipient. (Wrixon, 433).

Rangefinders 

A simple rangefinder uses two mirrors. One mirror, at one end of the baseline, is fixed at a 45 degree angle to the baseline. This stationary mirror is silvered on the bottom half but clear on the top half. The other mirror, at the other end, is a normal mirror, and is mounted so it can rotate. Look through the clear half of the fixed mirror at the target, then turn the rotating mirror until the object is visible in the mirrored half of the fixed mirror, too. A curved scale is used to trigonometrically convert the angular position of the rotating mirror into a distance to the target. The accuracy of the distance measurement is dependent on the length of the baseline; the longer it is, the better.

The first use of the rangefinder was in the military. According to W.L. Ruffell, "No serious attempts to obtain ranges by instrumental methods were made before 1770. That year saw the short base method put to limited use, e.g. for siege purposes, but it was a time-consuming process. Development of efficient optical rangefinders did not commence until 1860, at the start of the rifled era, and culminated in the introduction of the well-known Barr & Stroud types 20 years later."

By 1632, concave mirrors had been used to melt metals and to heat liquids (Butti, 33-34). Solar energy, concentrated by concave mirrors (or by biconvex lenses made of good optical glass), can be used to power solar stills, solar water heaters, solar cookers, solar pumps, and solar furnaces. (Butti; EA "Solar Energy"). This may not be very attractive in northern Europe, but some of the USE commercial ventures will be in tropical regions where sunlight is intense. Solar energy is particularly attractive in arid regions where there is no inexpensive alternative fuel.

"Industrial Glass," "Ravenscroft, George,"
Encyclopedia Britannica
(EB)

"Alkali Manufacture," "Aluminum," "Boracite," "Borax," "Boric Acid," "Colemanite," "Glass," "Kaolinite," "Lead," "Panderma," "Potassium,"
1911 Encyclopedia Britannica
(1911 EB)

"Boron," "Borax," "Glass," "Kernite," "Solar Energy,"
Encyclopedia Americana
(EA)

"Fiberglass," "Glass,"
World Book Encyclopedia
(WBE)

"Glass," Collier's Encyclopedia (CE)

Savage,
Glass of the World
(1973) (p. 45 says that French cast plate glass onto a copper bed)

Papert,
The Illustrated Guide to American Glass
(1972) (1865 recipe for crystal glass on p. 2.)

Douglas and Frank,
A History of Glassmaking
(1972)

Hynd, "Flat Glass Manufacturing Processes" (Chap. 2), and Wilson, "Tubing and Rod Manufacture" (Chap. 4), in Vol. 2,
Processing I
, of Uhlmann and Kreidl,
Glass—Science and Technology
(1980)

"Glass," in the Kirk-Othmer Encyclopedia of Chemical Technology 

Ellis, Glass: From the First Mirror to Fiber Optics, The Story of the Substance That Changed the World (Avon Books: 1998)

Macfarlane and Martin,
Glass: A World History
(U. Chicago Press, 2002)

Polak, Glass: Its Tradition and Its Makers (G.P. Putnam's Sons: 1975)

Diamond,
The Story of
Glass
(Harcourt, Brace: 1953)

Mehlman,
Phaidon Guide to Glass
(Prentice Hall: 1983)

"The Inventor of Float Glass,"

Pilkington company history,

 

BBCi, "Historic Figures: Sir Alastair Pilkington," http://www.bbc.co.uk/history/historic_figures/pilkington_alastair.shtml

"Float Glass"

 

Reat and Munley , "Justus von Liebig: An Educational Paradox," http://step.sdsc.edu/projects95/chem.in.history/essays/liebig.html

Smith, "Borax in Glass—Ancient or Modern?", Pioneer Magazine (January 1997), online

 

Chap. 18, "Spot and Roebuck (Acid)," in
Caveman Chemistry

 

Barbour, Glassblowing for Laboratory Technicians (1978)

 

Gregory,
Mirrors in Mind
(W. H. Freeman, 1997)

Newman, The Mirror Book: Using Reflective Surfaces in Art, Craft, and Design (Crown Pub., 1978)

Schiffer, The Mirror Book: English, American & European (Schiffer Pub., 1983)

Melchior-Bonnet,
The Mirror: A History
18 (Routledge: 2001)

Van den Muijzenberg,
History of Greenhouses
(1980)

Butti and Perlin,
A Golden Thread
(1980)

Holzmann, "MEMS the Word," Inc magazine (Nov. 15, 2000),

Rolak, "The Heliograph in the Geronimo Campaign of 1886." Military History of the Spanish-American Southwest: A Seminar. Ft Huachuca, AZ, 1976.

Wrixon, Codes, ciphers & other cryptic & clandestine communication: making and breaking secret messages from hieroglyphs to the Internet (Black Dog & Leventhal Publishers : 1998).

Ruffell, "The Gun: sights and laying—rangefinding" (1996);

 

Hochleitner, Minerals: Identifying, Classifying, and Collecting Them  

Fontana, Corrosion Engineering (1986)

Winder, "The History of Lead"

 

Lambert, Tracing the Past: Unraveling the Secrets of Archaeology Through Chemistry (Perseus Books: 1997)

"Boron Compounds (Oxides, Acid, Borates)," in the
Kirk-Othmer Encyclopedia of Chemical Technology
 

By Lisa Satterlund

By 1630, human beings had been using plants, animals and minerals to change the natural color of plant and animal fibers for at least five thousand years. The oldest written record of dye use goes back to 2,600 BC in China, and archaeologists have identified dyed textiles from about 1,400 years earlier than that. Vastly more is known about commercial dyeing than is known about early modern home dyeing. That doesn't mean that a lot is known about either. Dyeing was considered as much an art as painting, and rarely was the process documented before the latter part of the eighteenth century. Major sources of information about dyeing prior to that date are two dyers manuals that were published in the fifteenth and sixteenth centuries, manuscripts containing dye recipes other than the dyers manuals and economic records of towns and guilds. Next to nothing is known concerning home-dyeing prior to the revival of natural dyeing in the 1960s.

The first European commercial dyer's guide,
Mariegola Dell'Arte de Tentori
, was published in the early fifteenth century. Earlier works mentioned dyestuffs, the dye industry, and an occasional dye recipe. For example, a Greek manuscript known as the Stockholm Papyrus contains a recipe for imitation purple, and an Egyptian papyrus of 236 BC mentions dyers. Pliny the Elder talks about dye plants and bleaching with sulfur. For the most part, however, actual dye recipes were rarely printed. Dyers considered themselves artists, and guarded their recipes carefully. Years of development could go into the formulation of a good black dye, for instance, which would put that dyer's goods in great demand. Since reproducing colors with natural dyestuffs is never easy, the dyer could be fairly certain to maintain his position of superiority as long as the recipe did not become known.

The earliest colors that rated mention by ancient writers were reds, purples and blues; all dyed using natural materials that are known today and were major dyestuffs until the discovery of the first synthetic dye in 1856. Other subjects that ancient writers mention indicate that techniques such as printed fabric and batik are hundreds, if not thousands, of years old, as well.

Two major events in the history of dyeing during the early seventeenth century were the discovery of the effects of the use of tin as a mordant in 1630 by a Dutch chemist, and the beginning of the East India Company's importation of calico from India in 1631. The discovery that the Indians were able to produce brilliant colors and fancy patterns on cotton resulted in a drive by European dyers to reproduce the effects.

A. Before the fact

Plant and animal fibers can be dyed in the fiber (raw), as yarn or as fabric. The process for preparing the fiber for dyeing varies only slightly for the different forms, but can vary quite a lot between fibers. Linen and silk were rarely dyed raw, due to the vagaries of processing these fibers. The natural color of most wool, stream-retted linen and silk is slightly yellow. Dew-retted linen is grayish. For the sake of simplicity, this article will refer throughout to fabric as the item being dyed. Also, please look to the glossary at the end for definitions of dyeing terms.

The first step in preparing the fabric for dyeing was scouring. For wool this meant washing in stale urine or a solution of potash and water to remove the natural oils still present, as well as any oils added during processing. Even where the wool had been scoured on the sheep or in the raw, dirt was inevitably picked up during the weaving and had to be removed before dyeing. The ammonia in the urine and potash mix acted as a detergent.

Silk had to be cleaned before weaving, as in its natural state it was coated with a waxy substance called sericine, which made the fiber sticky and gave it a harsh feel. The method was fairly simple: the silk was boiled in a soapy solution for a number of hours. The removal of the sericine took most of the yellow coloring with it. The same process was followed after weaving to remove whatever dirt and oils were acquired during processing.

Cotton and linen, which not only contained natural waxes but were often coated with sizing during weaving, were fermented by adding bran to warm water into which the fabric was packed. Weights held the fabric down during the fermentation process, and it was important to remove the fabric before the scum created during fermentation settled into the fibers.

Once the fabric was clean, it was time for bleaching. Cotton and linen were almost always bleached before dyeing as the bleaching process helped assure that the fiber or fabric would dye evenly. Wool and silk were generally only bleached if they were to be dyed a light color. "Black" wool, which could be any color from tan to dark brown, would be used in its natural state.

Silk and wool were bleached by means of sulfur fumes. The wet fabric would be hung in a special room with pots of sulfur set on the floor. The sulfur would be lit and the room sealed until the sulfur burned out. This process was much faster than the method used to bleach cotton and linen, but was considered less satisfactory because sulfur-bleached fabric tended to turn yellow if not carefully handled. In addition, this method of bleaching did more damage to the fibers. While it is unclear how old this method is, the Roman Pliny mentions the use of sulfur for bleaching.

Cotton, linen and hemp, all cellulose fibers, were bleached in basically the same way. The fabric would be soaked in a mildly alkaline solution (often made from "rotten urine" or potash dissolved in water), removed and rinsed, then spread out in the sun. Depending on the time of year, the fabric would be moistened by dew or by being sprinkled with water. After some time in the sun, the fabric would be rinsed again, soaked in a mildly acid solution (often sour milk), washed, then returned to another alkaline bath. This process of alkaline bath, sun exposure, acid neutralization and washing would be repeated eight or more times, depending on the degree of whiteness desired. The entire bleaching process could take as long as eight months to complete.

B. Dyeing

Now the fabric was ready to be dyed. The first step was to obtain the dye. Commercial dyers bought theirs in the form of cakes, dried plants or wood chips. Home dyers, on the other hand, would have to gather the plants, lichens or other materials. This meant they needed to know which parts of which plants would produce the colors they were striving for.

Next, the dyer needed to prepare the dyebath, either by boiling and straining plant matter or by grinding prepared dyestuffs. Commercial dyers needed to know how many pounds of dyestuff were needed to dye large amounts of fabric, and trusted to experience (and the sellers of the dyes) for that information.