noon
It can be tinted to the taste of the purchaser ; but , as a rule , a tintless crystal is preferred . The entire work of building a large house , from the foundation to the finishing and removal of the metallic frames , occupies from half-a-dozen to eighteen workmen from four to eight days . This , like most other labour in Mars , goes on continuously ; the electric lamps , raised to a great height on hollow metallic poles , affording by night a very sufficient substitute for the light of the sun . All work is done by three relays of artisans ; the first set working from noon till evening , the next from evening till morning , and the third from morning to noon . The Martial day , which consists of about twenty-four hours forty minutes of our time , is divided in a somewhat peculiar manner . The two-hour periods , of which `` mean '' sunrise and sunset are severally the middle points , are respectively called the morning and evening _ zydau _ . Two periods of the same length before and after noon and midnight are distinguished as the first and second dark , the first and second mid-day zyda .