The subject of clocks leads me to mention what is perhaps not generally known, that as Nuremberg was the inventor of the watch (Nuremberg Eggs, shown in the Museum and the Castle), so also she invented a system of time peculiar to herself. To-day we have the Central Europe system (our 12-hour system), and the Italian or 24-hour system. But at the close of the Middle Ages the Nurembergers, the great clockmakers, had a third plan of dividing the day, called the Nuremberg great hour (Grosse Uhr), for which Regiomontanus drew out elaborate tables. Briefly the plan was this. At the equinox the night was assumed to begin directly after sunset, and day began twelve hours after sunset. This arbitrary "dawn" (_Garaus_) was sounded by the clock. To this day it is announced by ringing of bells from the principal churches. With the progress of the year, as the days after the equinox lengthened or decreased, time was added to or subtracted from the night or day. For instance, on the shortest day there would be 16 hours night and 8 hours day, and on the longest day 16 hours day and 8 hours night. Again, when the sun set at 6, the "Great Clock would strike 8 at 2 A.M., because 8 hours had passed since sunset. Seasons of the year were, in common parlance, denoted in accordance with this system. "At the time of year when the day strikes 13" would fix a date. The system, it will be seen, was almost as involved as the sentences of a modern German historian. But with all its drawbacks it lasted on, along with the Central Europe system, till 1806. Owing to the great elaboration of machinery required, the hours were usually struck by bell-ringers. But the clock of the Frauenkirche, owing to the additional mechanism needed for its toy-work, probably had to be fitted with the "little hour" from the first. Besides some old painted glass in the nave (coats of arms of Nuremberg patricians) and some carvings by Veit Stoss, the only works of art in the Frauenkirche that need detain us are the Pergenstorfer tomb (1499), at the end of the north wall of the nave, by Adam Krafft, and close to it the side altar-piece[62] (1440), which was originally the Tuchersche High Altar in the Church of the Carthusian Monastery. We have already had occasion to note more than once how the early Nuremberg painters, before Wolgemut, were struggling to achieve the simple portrayal of Nature and to combine it with the expression of their deep religious emotion. The picture before us is a very good example of this simple and yet sympathetic realism. Let us add that this quality, or combination of qualities, is not borrowed. For the Nuremberg School of Painting remains distinct and peculiar, with very little trace of foreign influence, long after the school of Van Eyck had made itself felt in the regions of the Lower and the Upper Rhine.