Stories in Stone (33 page)

He finished making a slate shingle by poking two holes into it with a treadle-powered hole puncher.
To this day, sculping
and splitting are crafts still done by hand.
Attempts have been made to mechanize but nothing has proved superior.

To facilitate their work, sculpers, splitters, and trimmers kept the slate wet throughout the entire process.
Like sandstone,
coquina, and limestone, slate hardens and becomes unsplittable as the quarry sap dries out.
Workers also had to worry about
slate in the winter because ice splits the stone.
In England, slaters described this process as the “hammer of frost.”

In addition to the costs incurred by hand splitting and sculping, slate quarrying suffered from waste, which ran as high as
90 percent in some quarries.
Many slate beds had too much sand, which made them unusable, but they were still in the way and
had to be removed.
Imperfections such as sandy ribbons or silica-rich concentrations, called knots, also marred good slate
beds.
And men made mistakes, lots of them.
At some quarries, the massive waste piles dwarf the surrounding topography.

Despite the waste, the slate industry grew rapidly after the Civil War and by 1876 American quarriers exported slate back
to England.
Few statistics exist prior to 1879, but between then and 1900 production tripled from 368,000 to 1.2 million squares
of roofing shingles.
One square equals a hundred square feet.
Slate roof production remained above a million squares per year
until World War I.
Throughout the years of peak quarrying, Pennsylvania generally produced twice as much slate as the next
most productive state,Vermont.

The vast majority of slate roofs are on the East Coast because the principal slate roofing quarries were nearby.
Slate covers
famous structures such as the original Smithsonian building and Vanderbilt’s Biltmore House, and institutional buildings such
as churches, schools, and government offices, but most slate went for commonplace structures such as barns, shacks, and homes.
There’s even a slate-roofed outhouse, built of wood with a Peach Bottom roof, in the old Welsh mining hamlet of Coulsontown,
Pennsylvania.

In the American West, very few homes sport slate roofs.
They primarily occur on institutional buildings.
For example, the
older buildings on the University of Washington campus, in Seattle, have slate roofs.
All of the shingles came from the East
Coast.

I didn’t discover slate roofing until Marjorie and I moved to Boston.
My first memorable encounter was at Harvard University.
Ornate and somewhat gaudy,Harvard’s Memorial Hall features a bold, striped pattern of green, red, and black slate shingles.
Most are the traditional square-cut pattern, but about halfway up the four towers, builders placed rows of green diamond-shaped
shingles.
Because this shape was not as watertight, builders used diamond shingles on steep sections, such as on mansard roofs.
Memorial Hall’s builders also used hexagonal shingles, which work better on less-steep roofs.
The building stands out for
its beauty and garish colors and shapes, especially in contrast to the stark concrete slabs of the nearby science center.

One of the great pleasures of living in the Northeast is exploring small New England towns and seeing the colorful slate roofs.
They come in shades of green, red, black, and purple with patterned and random blends of color.
Some ambitious owners went
to the trouble of laying the shingles so contrasting colors would shape out the numbers of the year the roof was installed.
One of the oldest dates from 1851, still with original shingles.
Not all buildings were in good shape; a run-down barn near
a friend’s house in Vermont looked as if the wood framing had pooped out and could barely support the weight of the slate.
I suspect that in a few years the roof would be all that remained visible, leaving a disturbing scene like that of the Wicked
Witch’s hat after Dorothy tossed water on her.
No matter the state of upkeep, slate roofs are part of what gives architecture
in the East an enduring elegance.

Slate sold well until World War I because it was abundant, nonflammable, durable, and fashionable.
Wood shingles were the
main competition.
They were cheaper than slate and generally available wherever trees grew.
Wood had one disadvantage, its
propensity to ignite.
Neither slate nor wood, however, could compete with the rise of asphalt shingles, which consist of a
mat of glass fibers coated in asphalt and covered in a protective layer of granules.
By 1947 asphalt roofing outsold slate
437 to 1.

Asphalt cost less and was transported more easily, and asphalt roofing sellers marketed their product better.
According to
Jeff Levine, the asphalt men further benefited from the parochial nature of slate quarrymen, who failed to adapt to new technology,
rejected the advice of geologists, and jealously guarded their trade’s skills.
Installing a slate roof also required skills
far beyond the rip-it-up-slap-it-down techniques of an asphalt roofer.

On a typical house, a couple of guys can start in the morning, tear off an old asphalt shingle roof, and have a new one installed
in a day or two.
No slate roofer could or would attempt such a feat.
They can put on one or two squares of slate per day,
compared with a nail gun–toting asphalt roofer’s daily output of twenty squares.
Not that nail guns have increased speed—experienced
asphalt roofers of old could install twenty squares per day with a hammer—but the mechanical nailers have made it possible
for novices to crank out roof after roof.

“I prefer working with a new guy than working with an experienced composition roofer when installing a slate roof,” says Ben
Kantner, who has been installing slate roofs for over twenty years.
¹³
“The new guys are slower and more careful.
It takes skill to set a nail right on a slate roof.
The comp guys tweak and pop
a lot of shingles because they bang in the nail.” Composition or asphalt roofs require pounding because the nail secures the
shingle in place.
Slate shingles, on the other hand, hang on the nail and can float, or move slightly.
To facilitate proper
nailing, the nail holes are beveled.
A correctly sunk nail nests in the bevel, neither sticking above the slate and preventing
the next overlapping shingle from laying flat nor going too deep and cracking the shingle.
Slaters also have to be able to
hit a nail straight because they often use copper nails, which bend more readily than nails made of stainless steel.
¹⁴

Slate roofing requires another precision skill, the ability to cut a shingle for spaces such as ridges, valleys, and chimneys.
Slaters employ either a modified paper cutter, like those used by trimmers in slate mills, or a slater’s stake and hammer.
With the stake and hammer, they lay a shingle on the T-shaped stake and chop it with the thin edge of the hammer’s shaft.
Slaters have to be careful because the edges of slate are extremely sharp; Kantner needed seventeen stitches when a shingle
sliced into his hand.
In contrast, cutting an asphalt shingle requires no greater skill than the ability to operate a utility
knife, part of the reason that a construction nincompoop like myself was able to reroof our house with asphalt shingles, although
it took almost a month.

A slate roof costs significantly more than a comp roof.
Installed asphalt shingles range from $50 to $150 per square versus
$500 to $1200 per square for slate, with additional installation costs of $12 to $30 per square foot.
Cost depends on color,
with red the most expensive, and size, with larger shingles costing more.
Slate shingles sell by size and range from six inches
by ten inches to fourteen inches by twenty-four inches.

“People would rather put their money in the interior than on the exterior of their home,” says Kantner.
“From my point of
view the exterior is more important.
That’s what protects the interior.” But since Americans are mobile people we don’t think
in the long term and if a roof lasts only fifteen or twenty years, we don’t worry because the leaks won’t be our problem.
We will have moved on.
Contemporary consumers seem to care little about permanence.
Slate and wood shingles were ideal products
in the 1700s and 1800s, when people moved less.
Having a good roof over your head was like having a good root cellar.
You
were planning for the future.

Using asphalt instead of slate reflects the widespread change in not using stone as much for building.
Slate had been the
most practical and popular roofing material, but the stone is so expensive to buy and install that only the wealthy can afford
to use it now.

Because of the dearth of slate roofs in most areas outside of the East Coast, about the only place to encounter slate regularly
is at a pool hall.
If you could look under the green felt of a pool table, you would find slate.
First used in 1826 by English
billiard table maker John Thurston, slate has remained the unrivaled material of choice for pool tables.
Thurston’s original
slate came from the Penryhn quarries in Wales.
He chose slate as a replacement for oak—the material he had used for a billiard
table sent to Napoleon in his exile on St.
Helena—because it didn’t warp, could be honed glassy smooth, and weighed enough
to prevent the careless, or unscrupulous, from bumping the table and repositioning balls.
Slate also was preferred because
of its low cost.

Pool arrived in the United States in the late 1700s, but not until the mid-1800s did it lose its unsavory reputation.
¹⁵
By then, several companies had begun to fashion tables, including the J.
M.
Brunswick Company, eventually the largest billiard
table maker in the world.
Brunswick originally obtained their slate from quarries in Pennsylvania.
No billiard table manufacturer,
however, has used American slate for decades.
It’s too expensive.
Everyone imports their slate from Brazil, Italy, and where
else, China.
It arrives precut and predrilled.
Each table consists of three pieces of slate, cut from one larger slab.
All
manufacturers use multiple pieces because one big bed is too heavy and awkward to work with and too hard to keep level.

I bring up billiards in part because of its reliance on slate, but also because a pool table led to the creation of one of
the few beautiful pieces of slate I have seen.
It is a relief sculpture of four ravens by Seattle sculptor Tony Angell.
He
had wanted to work in slate for many years but didn’t have the opportunity to do so until he pulled into a school parking
lot one day and saw an abandoned billiard table.
He salvaged the three pieces of the bed, taking home the one-inch-thick slabs
that weighed six hundred pounds.
(Robinson Jeffers also recycled billiard tables; slabs from Fort Ord form part of the path
at Tor House.)

The ravens face to the right.
Two have their heads raised slightly, perhaps alerted by the call from the two that have their
bills open.
Such a scene daily occurs in most urban parks.
Exploiting the slate’s fine grain, Angell carved exquisite details—shaggy
throat feathers, reptilian feet, and fine feathers on their beaks.
He also polished each bird so that they glisten like real
ravens illuminated by the sun.
Angell further highlighted the ravens by dulling the background with stippling and chipping
along the cleavage.
The patterns give the relief a surprising depth.
His sculpture brings to mind Michelangelo’s slaves; this
is clearly stone.

The relief of the ravens reveals another unusual aspect of slate.
It is the only building stone used primarily in two dimensions.
Slate is basically a material of length and width.
Consider its primary uses: roofing, blackboards, and billiard tables.
Each
use exploits how one can separate slate into thin sheets.
You will not find slate foundations or walls, places that require
length, width, and depth.
Coquina, for example, worked as a building material primarily because it could be cut into massively
thick blocks.
Builders don’t carve slate for three-dimensional embellishments, such as capitals or pediments, which makes
it more remarkable that slate serves so many purposes even though we don’t take advantage of all its dimensions.

The historic use of slate in schools and homes, and for recreational purposes, ensured that you would encounter slate every
day, but even after death slate could still play a visible role.
Boston’s King’s Chapel Burying Ground and most other old
burial grounds in the East are great places to see slate.

King’s Chapel contains several hundred slate tombstones in an area about as large as two basketball courts.
The slate grave
markers, now in several rows, were moved from a more haphazard setting into their present position by the superintendent of
burials in the early 1800s.
He thought it would make the grounds more attractive.
He also placed headstones along the paths,
giving you the ominous feeling that you are being herded unceremoniously across numerous graves.