even in the summer - As a pro- tection against wind and extreme cold and the formation of frost The whole upper part and ceiling of the room were lined with thin a tent lining of thin drilling. On three sides the room is double walled and covered with Cabot- sheathing and rubberoid roofing paper, except for window 10"x10" in size in the NW wall. Partition forming SW side is of single boards separ- ating room from rest of shed. Mr MacMillan determined meridian across middle of space chosen for seismograph by means of a first class transit the line and we marked it with a cord stretched between nails driven