This is a "hachure map"

Somewhere this weekend I ran across a reference to a "hachure" on a map, and had to look it up.  I assumed it had something to do with "cross-hatching" for shading.  Not quite.

Hachures are an older mode of representing relief. They show orientation of slope, and by their thickness and overall density they provide a general sense of steepness. Being non-numeric, they are less useful to a scientific survey than contours, but can successfully communicate quite specific shapes of terrain. They are a form of shading, although different from the one used in shaded maps...

Hachures are strokes (short line segments or curves) drawn in the direction of the steepest slope (the aspect direction). Steeper slopes are represented by thicker, shorter strokes, while gentler slopes are represented by thinner, longer and farther apart strokes. A very gentle slope or a flat area, like the top of a hill, are usually left blank. The hachures are traditionally monocolour, usually black, gray or brown; using two complementary colours for the hachures on a neutral background colour (e.g. black and white lines on gray map colour) would give a shading effect as if the relief were illuminated.

In representing relief with hachures on a map, six rules are to be followed, according to G.R.P. Lawrence (1979):

The hachures are drawn in the direction of the steepest gradient.

The hachures are arranged in rows perpendicular to their direction.

The length and thickness of each stroke represents the drop in height along its direction: a short and thick stroke represents a short and steep slope, while a long and thin stroke represents a long and gentle slope.

The strokes are spaced at an equal distance inside a row.

The strokes have the same thickness inside a row.

If the map is illuminated, strokes are thinner and farther apart on the illuminated side.

You learn something every day.

"Progressives" can become "left-wing Puritans"

Especially in matters relating to their children:

Today, of course, while the right still dabbles eagerly in the anti-fluoride, anti-vaccination, and other anti-science pathologies, the left may be the even greater culprit. Certainly the anti-fluoride coalition in Portland depended more on self-identified liberal voters than on conservatives. But there are key differences in how liberals and conservatives come by their fears. On the right, these mental illnesses stem from fear of government. On the left... they stem from an old mix of righteousness and the fear of contamination—from what we might recognize as Puritanism.

Let me give another example of left-wing Puritanism in action, one less glaring than the Portland referendum but which will be recognizable to many of you. Last month, at a birthday party for a three-year-old, I was hit with the realization that most of the parents around me were in the grip of moral panic, the kind of fear of contamination dramatized so well in The Crucible. One mother was trying to keep her daughter from eating a cupcake, because of all the sugar in cupcakes. Another was trying to limit her son to one juice box, because of all the sugar in juice. A father was panicking because there was no place, in this outdoor barn-like space at some nature center or farm or wildlife preserve, where his daughter could wash her hands before eating. And while I did not hear any parent fretting about the organic status of the veggie dip, I became certain there were such whispers all around me...

I was surrounded by the new Puritans: self-righteous, aspiring toward a utopian perfectionism, therefore condemned to perpetual anxiety—and in their anxiety, a threat to me and my children.

More at the New Republic essay, via The Dish.

Duluth's original "transporter bridge"

One of the landmarks of the harbor at Duluth, Minnesota is its aerial lift bridge (see photo at right).  Before the lift bridge was created, the canal was traversed via the "transporter bridge" (shown in the top photo) - the first of only two such bridges ever constructed in the United States (there are only twelve transporter bridges in the world).

When it was completed in 1905, the Aerial Bridge's gondola had a capacity of 60 short tons (54 tonne) and could carry 350 people plus wagons, streetcars, or automobiles. A trip across the canal took about one minute, and the ferry car moved across once every five minutes during busy times of the day.

Posted for reader Sarah, who lives in Duluth and who will probably be interested in this 1905 photo showing Duluth with no trees on the hill (?presumably as the result of prior logging?).

Top photo from Shorpy, and like all Shorpy images is best appreciated in the larger-than-wallpaper size at the original link.

Petri dish photography

In his lab at MIT, biological engineer Christopher Voigt has modified bacteria in agar to act like the light-sensitive silver halide crystals in gelatin emulsion on photographic film. He has hacked a harmless strain of Escherichia coli so that it produces black pigment when left in darkness or remains transparent when exposed to red light. He and his team modified the E. coli by adding 2 proteins from blue-green algae that recognize the red light and turn off the gene that makes the black color. The image is obtained by shining the red light through a printed transparency taped to the bottom of the petri dish. The process takes a few days, but the photo will last up to 3 years in a refrigerator.

Image and text found in Quigley's Cabinet.

A digital sundial

Like a digital clock, the digital sundial displays the current time using digits. In the true tradition of all sundials, the device is purely passive - it operates without electricity, and has no moving parts. Instead, the sunlight is cast through two cleverly designed masks in the shape of numbers that show the current time of day. The sundial is available in two versions, for use in either hemisphere. Placed on the inside of a south-facing window (north-facing in the southern hemisphere), the sundial can be read through the horizontal mirror. The display updates every 10 minutes, and gives a remarkably accurate record of the time during the daylight hours. 

More info at Digital Sundials International.

Changing household demographics

A graph of 40 years of data from the U.S. Census Bureau, shows that fewer American households are comprised of married couples with children.  Now there are more men and women living alone, and other "nontraditional" arrangements.

 

But the disconnect between those two trends may be felt the most strongly by people who live alone, whether they're 22-year-old women who aren't yet married, or 70-year-old retired widows. As more Americans are opting to live alone than ever before, that now seems like an entirely unremarkable choice. But for years we've been building houses for that big nuclear family that's now less common. And housing data released earlier this summer by the Census Bureau, illustrated at right, suggests that the U.S. is now a country where many people live alone in a land of 3-bedroom houses.

From The Atlantic and The Dish.

Plankton bloom

From NASA's Earth Observatory:

This photograph taken by an astronaut on the International Space Station highlights a late summer plankton bloom across much of Lake Ontario, one of North America’s Great Lakes. Microscopic cyanobacteria, or blue-green algae, can reach such large concentrations and color the water to such an extent that the change is visible from orbit.