hypocaust

Stephen P. Austin (CESWF-EV-EC)

> -----Original Message-----
> From: A. Goode & T. Kiser [SMTP:[log in to unmask]]
> Sent: Saturday, September 04, 1999 11:23 PM
> To:   [log in to unmask]
> Subject:      Mid-19th c. What is it?
>
> Greetings:
>
> I am excavating a domestic site in Gloucester County, Virginia, and
> have a ca. 1830-1870 feature which I hope someone on the list can
> identify. It is essentially a large, shallow firebox cut into natural
> clay, with a pattern of small flues down two sides.
>
> The main section is a rectangle, apparently a firebox, 11 feet
> long and 3.5 feet wide, with the narrow ends to the east and west.
> About a foot of topsoil has been removed, leaving the rectangle 0.4 of
> a foot deep. At the western end the natural clay is burned bright red
> over an area about 5 feet long, apparently the location of the stoke
> hole and the fire. East of this the bottom of the firebox is
> naturally-colored sterile clay, apparently the heat inside was not
> sufficient to affect this eastern area.
>
> The long sides have small projecting flues. On the south, these come
> directly off the firebox as projections about 0.9 foot wide, extending
> about 2 feet. There are six flues down the south side, about a foot
> apart, and the same general depth as the firebox. On the north there
> are traces of four flues of similar width, beginning at the eastern
> end and stopping about 7 feet down the side. The northern flues are at
> a slight obilique angle and do not connect to the firebox, with the
> original connection presumably bladed away. The floor of the firebox
> shows burn staining where these flues should have connected. Although
> the eastern firebox does not have burn staining, the flues in that
> area have been burned bright red with heat.
>
> The first stratum throughout the feature is predictably wood ash and
> the fill contains very few artifacts but includes sherds of
> gothic-revival whiteware. There is no obvious waste material, and no
> brick fragments. The site does have natural bog iron, and there were
> several chunks inside the firebox, but all of our features have bog
> iron. Whatever was being heated left behind no obvious remains, and we
> haven't sent off the soil samples yet.
>
> I am guessing there was a rectangular structure dug about 1.5 feet
> into the ground, probably just enough to allow them to create the
> flues down the sides. It was stoked from the western end, possibly
> accelerated with a bellows, and because of the flues, the structure
> could not be approached from the southern side or most of the northern
> side. It could be approached from the eastern end and at the
> northeastern corner, due to the lack of flues at that portion of the
> northern side.
>
> My first thought was a brick kiln, but there is no brick at all in the
> feature or around it. I am now wondering if it is actually for
> something like distilling or making molasses. My guess is that they
> may have been using a two-stage process, the first at the western end
> over the highest heat, then moving to a lower heat at the eastern end,
> where it was also possible to get to the heated material and
> manipulate it.
>
> My apologies is this is something exceedingly obvious -- I'm still in
> the field and haven't had a chance to go to the library. Any
> suggestions and possible refs would be appreciated.
>
> Thanks.
>
> Taft Kiser