Monday, November 12, 2018

Jedediah Hotchkiss' Sketchbook | From Library of Congress image gallery to mobile friendly PDF

I believe that Jedediah Hotchkiss' Civil War sketchbook would make for interesting reading. While this work is publish on the Library of Congress's (LoC) website, at 224 pages I wanted a more convenient way of reading the document than looking through an online image gallery.

Here's how I arrived at a single PDF file that contained all 225 pages of Jed's personal sketchbook.

Step 1: I viewed the source of the LoC page and noted a rel="alterantive" link tag.

Step 2: curling this URL returned back a wealth of interesting information:

$ curl -s  'https://www.loc.gov/item/2005625258/?fo=json' | jq .
{
  "articles_and_essays": [
    {
      "site": [
        "lcweb"
      ],
      "contributor": [
        "potter, abbey"
      ],
      "original-format": [
        "web page"
      ],
      "partof": [
...

Step 3: rather than reading the details of this JSON format, I poked around until I found this critical block:

    "resources": [
      {
        "files": 117,
        "captions": "http://cdn.loc.gov/service/gmd/gmd388m/g3880m/g3880m/gcwh0001/captions.txt",
        "image": "http://cdn.loc.gov/service/gmd/gmd388m/g3880m/g3880m/gcwh0001/ca000001.gif",
        "url": "http://www.loc.gov/resource/g3880m.gcwh0001/"
      }
    ],

Step 4: between curl and my browser, I was able to write the following code which pulls down all 117 images associated with this LoC entry:

#!/bin/bash

##
## Grab content from the library of congress
##
## For example:
##  locget 'https://www.loc.gov/resource/g3880m.gcwh0001/?c=200&fo=json&st=slideshow' 
##

usage() {
  echo "`basename $0` {gallery-url}"
  exit 1
}

if [ -z "$1" ]; then
  usage
fi

resource_url="$1"
captions_url=$(curl -s $resource_url | jq -r '.resources[0].captions')
image_url=$(curl -s $resource_url | jq -r '.resources[0].image')

path=$(dirname $image_url | sed -e 's|http://cdn.loc.gov/||' \
                              -e 's|/|:|g')

curl -s $captions_url | while read row ; do
  file=`echo $row | cut -f 3 -d ' '`
  if [ -n "$file" ] ; then
    curl -s "http://tile.loc.gov/image-services/iiif/$path:$file/full/pct:100/0/default.jpg" > $file.jpg
  fi
done

Note the call to tile.loc.gov to pick up the image files. By setting pct:100, I'm able to request full size images. It's also possible provide a value like pct:50 to pick up images that are half size.

Step 5: with step 4 complete, I had a full set of images locally. However, each image contains both a left and right hand page. To split the pages into separate files, I used my good friend ImageMagick:

$ mkdir pages
$ cd pages
$ for f in ../*.jpg ; \
   do echo $f ; convert -crop 50%x100% +repage $f `basename $f` ; \
   done

Step 6: Finally, I created a single (massive) PDF file by running the command:

$ convert *.jpg master.pdf

You can download the generated PDF here.

And here's a few screenshots of me scrolling throw Jed's sketchbooks on my Galaxy S9+:

The formatting isn't perfect, and the PDF file is massive. But still, I'm able to scroll through the pages with ease, and I can view detail by simply zooming in.

If I had a horse, I could peruse the content from the same perspective Jedediah created it. Though, even I admit that's probably excessive.

Wednesday, November 07, 2018

Same Signal Knob, Different View

Consider this drawing:

This scene took place on October 17th, 1864, just about 154 years to the day before Shira and I stood in the same location on Signal Knob. While Shira and I admired the tranquil views of the valley, Major General John B. Gordon and Jedediah Hotchkiss had an altogether different perspective. They were staring down at 34,000 enemy soldiers and pondering how a force less than half their size could defeat them.

Their assessment: we can take them. And so they did, two days later in the Battle of Cedar Creek.

After an audacious night march, Early’s troops forded the North Fork of the Shenandoah River and attacked the Yankees near Cedar Creek. The thick morning fog did much to aid the smaller Confederate force, concealing their numbers and causing confusion in the Federal ranks. The Southerners drove first one, then another, then a third Union Corps from their camps near Cedar Creek, across Belle Grove plantation, then north of Middletown. As the sun came up, it looked as if the Confederates had won an astounding victory.

It was a short won victory, however, lasting about 12 hours:

Meanwhile, word of the battle reached Sheridan, who was 20 miles away at Winchester. The diminutive Union chief saddled his prize horse, Rienzi, and rode furiously to the battlefield, rallying stragglers along the way. His arrival restored the spirits of his beleaguered troops who, Sheridan said, would be back in their camps by nightfall. Around 4:00 PM, the reorganized Federal host launched a savage counterattack for which Early’s men were ill-prepared and from which they could not recover. In the course of an afternoon, the Confederates were forced to yield the very ground they had captured scarcely twelve hours before. As the sun set over the Alleghenies, the Federals had not only regained the ground they lost, but had also extinguished any hope of further Confederate offensives in the Shenandoah Valley.

Still, what must it have been like to stand on Signal Knob, see a massive healthy force and see a tactical solution to defeating them?

The man in the drawing with the sketchbook is almost certainly Jedediah Hotchkiss. While Hotchkiss starts the war as a civilian teacher, he eventually becomes one of the Confederacy's most important weapons. His superpower: map making.

one of the Civil War’s most famous mapmakers, Jedediah Hotchkiss, was attached as topographical engineer on Confederate general Thomas "Stonewall" Jackson's staff, providing accurate maps that many historians believe played a central role in the success of Jackson's 1862 Valley Campaign.
...
There were very few maps for Hotchkiss to use as a base for his own work, and he usually rode out on horseback to survey the land himself. The Hotchkiss-Jackson collaboration bred success, for the general's lightning strikes depended heavily on making the most of the terrain. After Jackson’s death in 1863, Hotchkiss continued as a topographical engineer with the Confederate forces, frequently working personally for Gen. Robert E. Lee, but also traveling to Gettysburg with Lt. Gen. Richard Ewell, and later serving under Lt. Gen. Jubal Early, where one of his maps enabled the surprise Confederate assault at Cedar Creek in October 1864.

The Library of Congress hosts many documents and maps from Hotchkiss. My favorite so far is his personal sketchbook. The sketchbook includes this note on the front:

This volume is my field sketch book that I used during the Civil War. Most of the sketches were made on horseback just as they now appear. The colored pencils used were kept in the places fixed on the outside of the other cover. These topographical sketches were often used in conferences with Generals Jackson, Ewell and Early. The cover of this book is a blank Federal commission found in Gen. Milroy's quarters at Winchester, Jed. Hotchkiss

The sketches and notes in the margin are delightful. Using little more than colored pencils (and perhaps a straight edge?), he's created an impressive array of field expedient maps. They're part data, part artist creation. They're sort of terse visual poems that tell a story in a novel way. Man I love a well used notebook.

Here's a smattering of examples:

And so I close out this post with a challenge: I want to flip through Hotchkiss's sketchbook, but the Library of Congress site is too cumbersome to browse the entire collection. It's great for looking at a page here or there, but I really want to experience this as Hotchkiss did, as a handheld volume. So what's the best way to do this? Stay tuned, and find out

Update: See the answer to this challenge here.

Monday, November 05, 2018

Signal Knob Hike | 10 Miles of views, secluded wilderness and mountain bikers

Yesterday, the stars aligned and we had the time and weather to tackle the 10 mile Signal Knob loop located near Front Royal, VA. At an hour and half away from DC, this is a wonderfully accessible back-country adventure.

Two years ago, we completed most of the Buzzard Rock hike that's in the same section of the George Washington National Forest. They start down the road from each other. I was impressed with the area then, and I remain impressed.

Leaving the car, the weather was still in the low 40°F's. But the climb to Buzzard Rock Overlook more than warmed us up. Sunshine throughout the day ensured that we were never chilly after that.

Autumn colors were out in force this trip. As a bonus, the fact that so many trees had lost their leaves improved the views, providing for yet another reason to tackle this hike in the fall.

Folks report rocky sections of trail, which is true and does cause you to slow down a bit. But overall, there was nothing technical about the route and it was very well marked and maintained.

Speaking of views, this is one of my favorites of any hike. If you click on the image below, you'll notice a radio tower in the distance.

That radio tower is sitting on Signal Knob and in another 45 minutes, we'll be standing at the base of it. You encounter this view about 3 miles into the hike, have a mile to go before you're at the tower, and still have 6 miles left on the hike as a whole. I found these numbers humbling, to say the least.

We saw a handful of hikers, a couple of groups of backpackers, and most surprisingly, about 10 different cyclists on the trail. Apparently, the last 4 miles of trail are popular among mountain bikers. An impressive feat, but one I'll leave to others. I'll stick to walking, geocaching and snapping pictures.

Overall, it was an amazing day on the trail on a route that I can't recommend highly enough.

Friday, November 02, 2018

Blinking Lights and Duct Tape Make Everything Better

Last year, on the day before Halloween, I ordered this strip of LED lights for same day delivery. I wasn't quite sure what I'd do with the lights, but I figured they'd dress up any costume idea I'd come up with.

The LEDs showed up, and worked great when plugged into a phone-power pack. The provided remote control allows cycling through many color, fading and brightness options. Ultimately, I wrapped the LEDs around a broom handle, put on my Moroccan Djellaba, and ventured into the night as a wizard with a lit up staff. The LEDs were practical, though the effect wasn't as impressive as my mind's eye imagined. Meaning, they looked like a strip of LEDs wrapped around a broomstick, not some magic light emitting staff.

This year, I again found myself on October 31st with no idea what to do for a costume. I knew the strip of LEDs had possibilities, but I wasn't sure how or where to mount them.

Finally, a solution hit me. And of course, it was duct-tape based.

I laid out a strip of duct tape, lay the LEDs on one edge, and then folded over the other edge on itself. The result was a strip of LED lights with an adjacent bit of material.

I then grabbed my trusty Djellaba, and pinned the strip of LEDs into the hood (the qob, if you will):

While trick-or-treating, I could put up the hood, plug the LEDs into my backup-battery pack, and the result looked something like this:

Because the light was defused, it was more impressive than just seeing the strip of LEDs outright.

The result was certainly eye-catching, and more than one person commented on it while we were out trick-or-treating. Smaller kids were specially entranced by the effect. Oncoming traffic couldn't miss me. The only down side: depending on the brightness and positioning of the LEDs, I managed to totally blind myself. But hey, a small price to pay for looking cool, right?

Wednesday, October 31, 2018

A Lightweight Urban Exploration Adventure - The Historic Capitol Stones

I'm a fan of Urban Exploration Lite. That is, exploring hidden infrastructure, but the kind without menacing no-trespassing signs that would make the whole endeavor a crime.

Case in point: The Historic Capitol Stones. Located within Rock Creek Park is a collection of massive stones that used to be part of the Capitol building. In 1958, when the Capitol was renovated, the stones were put in Rock Creek park and promptly forgotten.

I've known about the pile of stones for years, but was just recently able to venture out and explore them in person. They did not disappoint, many having interesting markings or flourishes.

The location of the stones is an open secret:

The government neither discourages nor encourages visitors. The path to the stones is unmarked, but well maintained. If you do go, be careful walking around, and be gentle on the stones.

The Stones are 200 yards down an unmarked trail that runs southeast from the Rock Creek Stables.

I spent about 15 minutes exploring the site, snapping ample pictures. I was alone the whole time and as promised, there were no signs suggesting the area was off-limits. It's actually impressive how pristine the site is, especially given how accessible it is.

As for finding the site, you can use the directions described above. As an additional hint, here's my running route that took me adjacent to the stones:

Learn about the stones. Learn About Urban Exploration. Now go, explore!

Tuesday, October 30, 2018

Just how much is this going to hurt? A Strategy for Interpreting Raw Trail Data

A casual glance at this hike shows that it crosses an awful lot of contour lines:

But what does that mean in terms of level of difficulty? Is this going to be an exhausting slog, or a casual ascent?

Zooming in, it's possible to use the contour lines to derive the starting and ending altitude:

Which turns out to be 640ft and 1,040ft respectively. Also, using Backcountry Navigator it's possible to measure the distance between the two points.

Using this data, I now know that if we tackle this hike we'll be gaining 400 feet of elevation in 2.2 miles. But I'm still left with the original question: is this going to be an exhausting slog, or a casual ascent?

To answer this question, I decided I needed a PHC, a Personal Hill Catalog. That is, the stats on a number of local hills I'm intimately familiar with, that I can use to help interpret raw trail data.

My first attempt to setting up a PHC involved going to the hills in question and using my phone to collect the relevant info. You can see my attempt at doing this here. The problem arose when I compared the stats on my phone with Shira's phone for one particular hill. The numbers were way off, which lead me to question how accurately my phone can measure altitude.

Fortunately, there is a far more reliable way to get the elevation data I was after. Arlington County publishes a series of online maps, one of which includes topography. It's possible to know, within 2 feet, the altitude of any point in Arlington.

Using the topography map for elevation and Google Maps to measure distance, I was able to create my Personal Hill Catalog:

This spreadsheet consists of three base values: low elevation, high elevation and distance measured in feet, and a number of derived values (such as distance in miles, or slope percentage).

With my catalog in place, I was now ready to answer the question at hand: just how brutal would this hike to the summit be?

The slope of a 400 foot ascent in 2.2 miles is about 3.4%, which is surprisingly close to the Glebe, from 26th st to Walter Reed hill. I've walked this hill countless times, and while it's noticeable, it has a more or less gentle feel to it. This tells me that despite the crossing of so many contour lines, we have a do-able hike in front of us, and not some monster. I won't be able to declare the catalog a success until I've verified my assumptions in the field, but I'm amazed at the promise it shows with only a handful of local hills.

Incidentally, comparing my GPS readings with the Arlington County Map values shows that my phone wasn't especially off. In most cases, there was just a few feet difference, not enough to influence the catalog. Verifying the accuracy of my phone's GPS has been yet another benefit of this little project.

Monday, October 29, 2018

Some All Ages Halloween Crafting Fun

Check out these sweet 'jack-o-lantern' mason jar luminaries we made last night:

There's never a shortage of project ideas on the web, but finding one that's: (a) relatively substantial, (b) works for a variety of ages and (c) doesn't require a run to the craft store is harder than it sounds. Even I was surprised to find that I had jars, tissue paper and generic Elmer's glue lying around to power this project.

This project truly is fun for all ages, requiring little attention to detail to get excellent results. Both kids had no problem putting together their own lantern, and even I took a few minutes this morning to make one for myself. The variety of jar sizes and tissue paper colors only helped make the project more interesting.

Perhaps most importantly, I was exposed to the power of watered down Elmer's Glue. Who knew that this stuff was so useful?

If you're looking for a last minute, fun for everyone Halloween project, this is it.

Detailed instructions are found here: Easy Halloween Luminary - Great Jack O'Lantern DIY.

I'll never look at an empty jar of salsa quite the same way again...

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