细节
Three calculators:
a Halden Calculex double-sided circular slide rule with instructions in aluminium case; a Fowler's double-sided Textile Calculator in fitted case; and a Fowler's double-sided calculator in leather pouch (2)
a Halden Calculex double-sided circular slide rule with instructions in aluminium case; a Fowler's double-sided Textile Calculator in fitted case; and a Fowler's double-sided calculator in leather pouch (2)