This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
147. The new wall under the needle holes is built up from the lower level, between and around the needles. It is customary in first-class work, to place two layers of stone, dressed top and bottom, between the old and new wall. Iron wedges are then driven between these stones, in opposite pairs, one from the inside and the other from the outside, care being taken to drive them evenly from both sides, or the wall may tip or bulge. The wedges are driven until the weight of the wall is carried on them and not on the needles. This can be readily seen by the straightening of the needles when relieved of the load. The jack-screws are now loosened, or the wedges under the uprights eased up; the uprights are taken away, the needles are removed, and the holes filled up.
148. Underpinning operations should be carefully performed. The underpinning should be done as quickly as possible after the shores or needles are in place, so as not to require their support for a longer time than necessary. The needles or shores, however, should not be removed until the cement in the new work has had ample time to set.