Mosaic Philosophy

SECTION I, BOOK I, CHAPTER III.

Here is described the construction of this organ or instrument, which the common people call a "calendar mirror," along with the preparation of the glass and the fitting of its opening or "nose" into a small vessel full of water; wherein also the opinions of those who think that water is sucked out and raised into the neck of the glass or flask by heat are deservedly refuted. original: "speculum calendarium". This instrument is an early thermoscope, a precursor to the thermometer, used to observe changes in air temperature.

It must be observed first of all that this experimental instrument of ours is composed of three parts; two of which belong to the nature of the machine itself—namely, the Flask original: "Matratium", a long-necked glass vessel used in chemistry or glass, and the lower vessel full of water into which the nose or opening of the glass must enter; the other part is more accidental, being so arranged that it supports the glass in its perpendicular position.

As far as the flask or glass is concerned, it ought to have a sufficiently spacious head, either round or oblong, with a long and narrow neck, whose opening or mouth must be proportioned to the rest of the neck and prepared and fitted in a twofold manner. For first, its neck, placed perpendicularly, is to be fitted into the small vessel or basin full of water in such a way that its opening touches the bottom. Then, from the surface or top of the water, and ascending upwards through the neck of the glass to its globe, we must measure until we reach the ball itself—whether it be long or oval—and divide that neck into 15 parts. In the middle of these, specifically between its head and the surface of the water at the bottom, I mark the figure I. Then, descending from I. and likewise ascending from I., I number and mark 1. 2. 3. 4. 5. 6. 7. For example:

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original: "Hyemis Dominium". This refers to the upper half of the scale where the water rises as the air in the bulb cools and contracts.

A scientific diagram of a "speculum calendarium" (an early thermoscope). It consists of a large glass bulb (matratium) at the top with a long, thin neck submerged at its base in a small cylindrical vessel of water. The neck features a vertical scale. A central horizontal line is marked with the numeral "I" and labeled "Sphæra Æqualitatis". Above this line, the neck is graduated with numbers 1 through 7 ascending towards the bulb. Below this line, it is graduated with numbers 1 through 7 descending towards the water. Dotted lines form a narrow conical shape around the neck of the glass.

original: "Sphæra Æqualitatis". The neutral midpoint of the scale representing temperate conditions. original: "Æstatis Dominium". The lower half of the scale where the water level drops as heat expands the air in the bulb.