|Mercerised cotton top by Zalora. I apologise for the lack of glam. Standing around like a clothes hangar seems to be the default approach to modelling mercerized pictures. The men in t-shirts do better with what they have, but here I exercise my male privilege.|
|Chintz top By Nasty Gal|
|The kind of flouncy effects the reader |
probably associates with "chintz" and "crepon."
Otravez by Di Anna Elardo.
David Rance of Slide Rule Gazette tells me that William Twaddell (1792--1839), apprenticed in the shop of James Brown, "renowned Glasgow instrument maker") before branching out on his own. He is first known to the collector from a set of "philosophical bubbles," which is a matched set of eighteen hand-blown glass bubbles. You throw them in the retort, and the one that floats to the surface tells you the specific gravity. As you keep adding one thing to the other thing, one bubble after another floats to the top, until you get the one you want, at which point you should stop adding. Philosophical bubbles were a well-known product, marketed to the spirits and liquor industry. Subsequently Twaddell made hydrometers
|The Twaddell hydrometers Mr. Mercer would have used.|
Again, it's just my inference that Mercer used his Mercerising process to make flouncy, chintzy fabrics suited to early Victorian tastes. That, plus it is an excuse to put that nice picture up! When Mercerisation was reinvented, it was because they had those grabby things that prevented shrinkage, but also because caustic soda was a lot cheaper. What I am circling back on is that going to come back to here is the notion that exposing fabrics to the effect of "concentrated caustic soda" was some kind of novel discovery of 1844. Traditional batik-making involves
"Firstly, a cloth is washed, soaked and beaten with a large mallet. Patterns are drawn with pencil and later redrawn using hot wax, usually made from a mixture of paraffin or beeswax, sometimes mixed with plant resins, which functions as a dye-resist. The wax can be applied with a variety of tools. A pen-like instrument called a canting (Javanese pronunciation: [tʃantiŋ], sometimes spelled with old Dutch orthography tjanting) is the most common. A tjanting is made from a small copper reservoir with a spout on a wooden handle. The reservoir holds the resist which flows through the spout, creating dots and lines as it moves. For larger patterns, a stiff brush may be used. Alternatively, a copper block stamp called a cap (Javanese pronunciation: [tʃap]; old spelling tjap) is used to cover large areas more efficiently.
Emphasis mine. "Caustic soda" has another name, after all: soap. Or, rather, it's the active ingredient in that somewhat magical stuff. Home-made NaOH solutions have been used to treat fabric for a long time before Mercerisation was thought of. In fact, I've cut off a subsequent use of caustic soda in the preparation of indigo dye from the indican precursor produced from natural indigo plants. What Mercer discovered was a specific post-production treatment of a specific kind of cloth. As we learned from Fortune, there was a raging debate about just what Mercerisation did to cloth that continued into the 1940s and the invention of the electron microscope. From this perspective, I'm at least open to the idea implied by some sources, that what Mercer was trying to do was develop a new way of filtering caustic soda. In short, he was trying to improve caustic soda production with a view to making more of this essential material available to the existing textiles industry, for work such as calico printing. Instead, he stumbled on a new way of using caustic soda to produce a unique and valuable textile product.
It's a story, anyway. It's also bound up in the instruments. Mercer has a new set of Twaddell hydrometers that allow him to assess the merits of a caustic soda solution in a new way. He sets out to produce caustic soda at a specific Twaddell number, and ends up showing that caustic soda of a certain Twaddell rating has this novel effect. Mercerisation helps sell the Twaddell scale, and Twaddell hydrometers.
John Brown may have been a "famed instrument maker," but good luck tracking down a specific Glaswegian named John Brown. By the time Archibald Barr and William Stroud were "approached by the Admiralty with a request to develop a short-based rangefinder" in 1891, Mr. Twaddell had been out on his own for more than seventy years, and, well, speaking of the latest run of Engineering, here's a link to the 1896 edition of The Electrician Electrical Trades Directory and Handbook, so you can see that there were lots of people and firms named "Brown" in the trade in Glasgow by then. This was two years before Archibald Barr was called home to Glasgow to take a chair at the University, and three years before his revived connection with Stroud, a former colleague at Leeds College, led to the opening of a manufacturing facility in Glasgow to produce the already-mentioned rangefinders.
Unlike some of the other old firms we've followed up on around here, Barr and Stroud didn't move into a palace:
which is nice, because if they had, they would have outgrown the Anniesland neighbourhood, and I wouldn't have an excuse to post this aerial:
|Mid-Eighties Anniesland. Quaint! Photo from the blog, Lost Glasgow, by Dennis Thompson.|
|Lomb factory in Rochester, New York|
If I understand it properly, the multiplex stereo mapping equipment consists of several projectors mounted above a movable tracing table, which is above a drawing table. The projectors are fed with several overlapping aerial photographs, which are projected in blue and red onto the tracing table and then [something something] adjusted so that they show one particular datum, or elevation, which becomes a bunch of blotches. Trace the outlines of those, and you have all the given contour lines at that elevation on your final mapsheet. Keep on adjusting to produce slices of at each contour line, and eventually you will have a complete contour map.
|Now that's Dieselpunk. Source.|
It's too bad that we don't have a similarly loving description of the multiplex stereo mapping equipment used by the USGS previously. It might well have been made abroad, as the USGS had a distinct preference for Zeiss equipment at the time. But it turns out that by attaching "Barr and Stroud" to my search, I am led to a bonanza of work coming out of the Barr and Stroud archives. Fancy that! Here's a snip from Petrie's Short History of British Stereo Plotting Instrument Design that was Archibald Barr's initial contribution to the problem.
|The Wiki article doesn't really get at the|
sheer assholeness of the man.