A groin is the edge line formed by the meeting and intersection of any two arched surfaces. When this edge line is covered and emphasized by a band of moulded stones forming an arch, as it were, on this edge, this is called a groin rib.
The "D" seems to have been accidentally omitted in this diagram; it is of course the fourth angle of the plan.
This was illustrated by diagrams on the wall at the delivery of the lecture.
THE METEOROLOGICAL STATION ON MT. SANTIS.
At the second International Meteorological Congress, in 1879, the erection of an observatory on the top of a high mountain was considered. The Swiss Meteorological Commission undertook to carry out the project, and sent out circulars to different associations, governments, and private individuals requesting single or yearly contributions to aid in defraying the expense of the station. In December, 1881, an extra credit of about $1,000 was granted by the Bundesversammlung for the initial work on the station, which was temporarily placed in the Santis Hotel, and a telegraph was put up between that place and Weisbad in August, 1882, so that on September 1 of the same year the meteorological observations were begun.