This is here for the convenience of members of the BSS while the content is being transferred to the new site.
Pages: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Introduction Dial types Hours (types of) Time (types of) Illustration
Symbols Equations Biographies Chronology Sources Appendices
: the central, darkest portion of a shadow, i.e. the region which does not receive direct rays from any part of a distributed light source (e.g. the Sun).
umbra recta
Latin for “upright shadow”, it is the label often found on the cotangent scale of altitudes < 45ยบ
on a shadow square.
umbra versa
Latin for “reverse shadow”, it is the label often found on the tangent scale of altitudes > 45ยบ
on a shadow square.
Universal Time (UT
): see time (types of).
Pages: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Introduction Dial types Hours (types of) Time (types of) Illustration
Symbols Equations Biographies Chronology Sources Appendices