XI. MISCELLANEOUS. 379 



by two projecting catches. The light, after passing through a condensing lensj 

 is received by a rectangular prism placed at such an angle that the beam is 

 totally reflected downwards into the window of the telescope, where its inten- 

 sity and colour are modified by diaphragms. The lamp is suspended on a 

 pivot, and also the framing and prism-box revolve from the bottom of the 

 supporting pillar, so that it has a universal motion accommodating it to the 

 position of the telescope. The weight of the end counterpoises the lamp, and 

 the one at the side is the gravity poise. The top of the lamp is movable, and 

 has attached a small tin chimney, which assists in promoting a draught 

 and keeping it cool. 



1924. Perpetual Almanac. 



(Directions for use printed at the back.) 



Gust. Schubring, Erfurt. 



1924a. Calendar for Two Thousand Tears. 



M. Georges Sarasin, Geneva. 



Lithographed sheet, framed and glazed, permitting the sight, by three 

 openings, of portions of a second lithographed sheet which is capable of move- 

 ment round a spindle issuing from the right side. These lithographed sheets 

 are divided into sectors of a circle radiating from a common centre, which is 

 at the same time the centre of motion of the second. They are covered with 

 figures and explanations. An inscription denotes briefly the method of use. 



USE. If, by the motion given to the central disc by means of the spindle, 

 the two figures which express the tens and units of a year, and the figure 

 which constitutes or the two figures which constitute the hundreds 

 (whether according to the Gregorian or Julian style), be brought into such a 

 position that the latter be to the left tind the former to the right, the calendar 

 of that year will be given on the lower portion of the sheet. The days of the 

 week will correspond to the days of the month in the radial direction, and to 

 the months in the circular direction, whichever of the two styles may have 

 been chosen. There is no occasion either to give a new movement to the disc, 

 or to take into consideration the dominical letter, which is only a digression. 

 Two of these data being given, the third may be found. When the three 

 data are given, the years may be found, which, since the Christian era, have 

 possessed them ^together. 



The months of January and February are distinct according to whether it 

 be a bissextile or ordinary year that is in question. In the former case, the 

 tens and units figures, divisible by four, are separated by an empty space from 

 the preceding in the table of years. A third designation of the two above- 

 mentioned months is also perfectly suitable to the two classes of years, if the 

 date of the year immediately preceding be formed by the movement of the 

 disc. 



It may also be ascertained to what day of the ordinary week corresponds 

 any date during the thirteen years of the Republican style which followed the 

 year 1792, by taking for the hundreds portion the zero of the Julian style. 



1924c. Calendarium Ferpetuum Mobile, eight Tables in 

 glazed frame and in a stand. Ch. A.. Kesselmayer, Manchester. 



A perpetual calendar, which gives the solution of any chronological problem 

 during a period of from 10,000 years before to 100,000 years after Christ. The 

 tables, which are still in course of construction, will contain the principles of 

 a " Standard Calendar," as invented by the author, the object of which is to 

 demonstrate the errors and inaccuracies both of the Julian and Gregorian 

 calendars. 



