Sundials - World's Oldest Clocks

North American Sundial Society


Sundial 35
State/Province:  Pennsylvania Country:  USA
Dial Type:  Vertical Decliner Condition:  
Latitude:   39° 54' N Longitude:   75° 21' W
  • Swarthmore College
    College Avenue
    Kohlberg Hall
  • Modern design for a vertical dial declining 20.5? east on a brick wall. The gnomon is a twisted sheet of bronze, casting shadows onto granite hour marks. The dial was designed by Marti Cowan using Waugh's formulae for vertical dials. Frederick Orthlieb, professor and chair of the Dept of Engineering at Swarthmore "had a part in locating the bent-plate gnomon so as to give correct indications on the vertical wall? As installed, the gnomon's indicating edge (which lies on a Polar Axis) casts a quite short shadow in Autumn and Winter and requires some observing skill to make a close estimate of indicated time, but in Spring and Summer the longer shadow moves over the granite hour marks very plainly."
General Information:
  • Owner: Swarthmore College
  • Designer: Marti Cowan of Margaret Helfand Architects in NYC
  • Builder:
  • Construction Date: 1995