Of Nebulae and Drawings

I noticed a slight error that seems to be floating around out there on the net. Several “this day in history” sites, including the Wikipedia page on 4 March list today as the “first sighting of Orion Nebula by William Herschel” in 1774. Strictly speaking that’s not untrue—Herschel seems to have made his first observations of the Orion Nebula on 4 March 1774, but in fact, telescope observations of the nebula had originally been described by Peiresc back in 1610 (cf. a lengthy list of early observations of deep-sky objects).

What’s important about Herschel observing Orion is that it got him started on a massive cataloging campaign that resulted in a list of thousands of deep-sky objects. And a numbering system that’s still in use today!

All this thinking about the Orion Nebula reminded me of the image shown above—a sketch by William Herschel’s son John. I link to a fine-art print offered by David Malin of the same, and in a continuing cascade of connections, I also wanted to point out a marvellous essay by Malin in which he compares Herschel the Younger’s drawing to (a somewhat more psychedelic) one created by William Parsons. As he points out, differences between the two images “result not from changes in the nebula or in telescopic power, but from subjective differences in the way their creators saw, remembered, and sketched what was essentially the same subject.” I’ve blogged about related issues before, but Mailin is both nicer and more eloquent than I.

Anyway, I hope you appreciate a random stroll down this-day-in-history lane.

How Do You See Invisible Germs?

Sorry for the gap in posts, but the last few days have been a little hectic. And I suppose it’s appropriate that I seem to be coming down with a bit of a cold as I decide to write about The Gospel of Germs by Nancy Tomes. I just finished Tomes’s book last week, and it inspired me to think about how the invisible is visualized in a popular context. Her perceptive and illuminating book describes the acceptance and interpretation of the germ theory of disease around the turn of the last century—from advertising to anti-tuberculosis societies, from labor unions to Listerine. Fascinating stuff.

Because 19th-century microscopes didn’t really allow for photography (I tried searching for when the first photographs were taken through a microscope, to no avail, but I’ll update you if I learn anything), drawings of microbeasties had to stand in for actual photos. Of course, the same was true of most imagery that appeared in a newspaper or magazine of the day—it all had to be represented in etchings or lithographs (the first newspaper photograph appeared in 1880, although I admit that my source is a little off the beaten track). Unfortunately, I couldn’t find images online to help me illustrate the concept in the context of that time period. But the above drawing, which comes from a web page about “Infectious and Epidemic Disease in History” from the University of Califoria Irvine, underscores the basic idea.

I have previously commented on the unreliability of drawings compared to less subjective means of recording data, but Tomes’s book and the drawing above raise another issu: when the subjective role of illustration actually takes precedence over its objective goals. The point of the cartoon is not to communicate what a germ looks like—instead, it simply stands in for an unseen critter that obviously poses some kind of threat to us. It looks like a nasty bug. Indeed, some of the illustrations that appear in Tomes’s book use the same visual vocabulary—the insect-like features, the hairiness—to communicate the same thing (albeit not in such a cartoonish manner). Look at the iconography that surrounds the ever-popular Airborne® health formula, with its colorful, slightly creepy but mostly effete and harmless “bugs.” A little bit of the 19th-century threat remains, but the slightly bowdlerized images allow us to view the microscopic world as something fundamentally under our control.

Nowadays, when the variety of imagery available to us via microscopy, we can think of the microscopic world as incredibly detailed, fluorescently colored, or perhaps confusingly abstract, a cartoon like the one above is easily interpreted for what it is. But when an image represents a new concept, it’s all too easy for it to become literalized. I don’t know how many people at the end oft he 19th century perceived newspaper and magazine ad illustrations as true depictions of the (quite threatening) microscopic world, but surely the less cartoonish, albeit similarly demonizing, illustrations had an effect.

The Way of the Dodo

Like many research organizations, the Royal Society has a “Picture of the Month” that it displays on its web page. This month, they reproduce the image above, a 19th-century lithograph based on a 17th-century oil by Roelandt Savery. I would like to draw your attention to a critical attribute of this lithograph: it sucks. Particularly if you have no idea what a dodo looks like.

Comparing the above image to Savery’s most famous oil of a dodo, it seems as though the 19th-century copyist (somebody named “Erxleben”) may simply have lacked talent. Admittedly, the caption on the web site indicates that it merely reproduces “a small detail” of the lithograph, but even at that, it’s hard to take the person’s skill seriously.

I choose this image to highlight how far we’ve come. Three-dimensional computer reconstructions and digital images from spacecraft a billion miles from home are only the tip of the iceberg! We have a plethora of techniques to take scientific data and transform them into pictures. But the work started with scientists and artists putting pencil to paper, or brush to canvas, or crayon to limestone,… Photography, of course, only started in the middle of the 19th Century, and digital imaging techniques are thirty-some-odd-years old.

What we now take for granted is the fidelity of a representation to its sources. Specialists might quibble over the use of color or the “fixing” of errors such as bad pixels, but fundamentally, we all think of contemporary visualizations as accurate in a way that few drawings or paintings, even those executed by gifted artists, could ever hope to be. When you couple that inherent limitation with the potentially incompetent skills of a secondary or tertiary artist such as, say, Erxleben, then you quickly see how successive copies of a work used to grow worse over time. (For another good example, compare Galileo’s orginal delicate watercolors of moon phases with the respectable engravings he commissioned for Siderius Nuncius as well as the mediocre woodcuts that appeared in a knock-off, unauthorized printing of the same.) We no longer need to worry about such things.

Of course, there are plenty of other things for science visualizers to worry about (or at least consider and mull over). That’s why I started this blog, after all…