6 THENEW-YORKHISTORICALSOCIETY occupants are able to recall the changes made. Valuable information is often found in the papers of persons no longer living, in old insurance policies, and on old property maps of the city which have been preserved. Court records, when available, contain interesting evidences. Archaeological investigation reveals foundations of portions and dependencies which may have been destroyed. With this information in hand, the building is dismantled, often to its frame. This permits the study of its construction and reveals any unsuspected alterations which have been made in the past. It also permits the replacement of decayed materials, although every piece of old material which is sound is retained. In ' some cases it is necessary to raise the building with jacks and replace decayed foundation walls and sills. With this work accomplished, the building is reassembled, the old materials which are sound and accurate being used. The building then is replastered by methods employed by colonial plasterers. It is redecorated according to the available evidences of its original decorations. Where evidence is lacking, precedent established by similar houses of similar date is resorted to. "The Sir Christopher Wren building of the College of William and Mary may be cited as an extreme example of the work in this division. The appearance of this building had been changed by two fires and consequent renovations from the appearance it presented during the period to which it was to be restored. The period to which it was to be restored was divided from the earliest period of the building by another fire and renovation. The walls were largely original, but in a weakened condition. Research work by the Restoration and College provided complete pictorial evidence of the exterior design and detail of the building and a floor plan of its interior during the period to which it was to be restored. This evidence was substantiated by archaeological and architectural examination of the walls themselves. It was further substantiated by extensive written evidence which was collected. A concealed steel frame was inserted in the walls to strengthen them and to carry the new interior construction. The walls were strengthened further with a concrete solution which was forced into them under high pressure. Exterior and interior woodwork, entirely destroyed by fire in 1859, was duplicated and replaced according to evidence in hand. The building was replastered and painted. It is impossible to outline the difficulties which confronted this work and explain their solutions in a publication of this nature. It may be said that the building at the outset of its restoration presented one of the most difficult and one of the most important architectural problems in America. "Procedure in the restoration of homes and buildings which have disappeared involves more extensive research work. In some cases the buildings are replaced with old buildings of similar design and date, which are moved bodily into the restoration area or are dismantled elsewhere and reassembled on the site. More often they are rebuilt with similar materials and by methods similar to those employed in their original construction. In practically every case, excavations reveal the original foundations, which are invaluable in substantiating pictorial and documentary evidence.