Alex,

It looks like a rather typical water storage cistern; rainwater from roofs 
was collected by guttering and downspouts and piped into the underground 
tank. The bottom is likely bricked, but probably about 1.5-2m deeper than 
you reached. They are common in areas of the country not blessed with 
shallow and potable ground water (in a swath of country with a dearth of 
wells there is usually a surfeit of cisterns).

Best regards,
Bob Skiles

--------------------------------------------------
From: "Alexander Keim" <[log in to unmask]>
Sent: Tuesday, November 16, 2010 10:26 PM
To: <[log in to unmask]>
Subject: Help identifying a 19th C. subsurface feature, a dry well?

> Hello! My name is Alex Keim, a PhD candidate in Historical Archaeology at 
> Boston University, and I am hoping someone can help me identify a 
> architectural feature I encountered while doing a on-site consultation in 
> Lynn, MA. A link to photos is at the bottom of this message. The feature 
> is located in the rear lot of a townhouse constructed in 1871. The feature 
> in question is the remainder of a previously partially demolished brick 
> dome or vault, about 1 meter below current surface level. Based on 
> photographs (see link) of a very similar feature uncovered by construction 
> crews about 30 meters away (but reburied before I could see it firsthand) 
> I believe the feature was originally a dome with a circular opening at the 
> top. This intact feature also had metal piping entering the dome near the 
> base, but the partial feature I encountered had no surviving piping. The 
> dome is roughly a meter from top to base, and the intact portion I saw was 
> about 2 meters in diameter. The feature is
> constructed of bricks and mortar. It is set on a large circular pit, full 
> of cobble sized rubble and rip-rap. I partially excavated the soil fill 
> above the rubble and determined that it dates to after the feature's 
> demolition, and I removed a portion of the rubble fill to try to determine 
> the depth of the hole, but I encountered no sign of a bottom after 70 cm.
>    I am thinking that this is some kind of dry well, or possibly a 
> cesspool (but there were no cessy conditions or residue on the interior), 
> but I have never dug something like this before and would welcome 
> confirmation or other interpretations. If anyone has encountered a similar 
> feature I would greatly appreciate some feedback. Following is a link to a 
> webpage that should give you access to some photographs of the intact 
> feature I did not see firsthand, and the partial feature I worked on. 
> Thanks for your time!
>
> Sincerely,
>  Alex
>
> http://img72.imageshack.us/i/intactbrickvaultfeature.jpg/
> http://img512.imageshack.us/i/afterpartialremovalofru.jpg/
> http://img204.imageshack.us/i/detailoffillremoval.jpg/
> http://img217.imageshack.us/i/featureafterexcavationb.jpg/
> http://img594.imageshack.us/i/featureafterexcavationb.jpg/
> http://img143.imageshack.us/i/featureafterexcavationb.jpg/
> http://img138.imageshack.us/i/intactbrickvaultfeature.jpg/