Appendix: 'On architectural structures suitable for astronomical observations', folio 40r

ON ARCHITECTONIC STRUCTURES SUITABLE FOR ASTRONOMICAL OBSERVATIONS

The description of astronomical instruments given above in such a manner as found expedient, more than sufficiently treat the mechanical part of the art, which ought to precede everything else, and without which it is no use entering on the rest, and by their not only pleasant, but also useful and almost necessary variety and abundance they serve all kinds of purposes completely. But if these instruments should be able properly and without difficulty to serve the purpose for which they are intended, not only a place is required, but also proper buildings, where it is possible without difficulty or disturbance of any kind to do this work. First of all, the place should be in a high locality from where there is a free view round the whole horizon, without woods or mountains or other buildings intervening. It is also preferable that it is a solitary place, free from the commotion of the common herd, where it is possible to enjoy philosophical tranquillity, although so that the things needed are available and learned and intelligent persons can frequently be admitted, while the common herd, which is no judge of such things or does not attribute to them the value they deserve, can be excluded. And even though the more southerly regions, where the orbits of the stars stand more vertically on the horizon and the heavens are more frequently bright, might be thought preferable to those closer to the poles and more northerly or arctic - as in my country, it is not opportune for everybody for that reason to leave his native country or the place where he lives, and perhaps lie cannot either, in all more southerly regions of the earth, particularly in unknown and foreign countries, succeed in finding the conditions and facilities needed, and so he must content himself with the conditions of place and time offered to him and which he may obtain, and with constant care try to surmount the existing difficulties and inconveniences, in order that things should not turn out as said by Seneca of Time: "We have not enough of it, but we waste much of it. " It is true that in Egypt and other regions of Africa and Asia, where the ancient astronomers lived, it was easier to get an opportunity for such works, because the heavens are said to be brighter there and the orbits of the stars have a steeper inclination; but as Bellona under the reign of the Turks has driven away nearly all free sciences from there, it is only natural that Astronomy should be in exile, too, or be held in less esteem in these countries, except in so far as it is perhaps in a certain way cultivated by the Arabs. As to other regions of Europe situated in the south, we might at any rate cherish greater hopes in so far as they are not ruled by the Turks or the Muscovites, as they do not there disdain the free sciences, but, as also most of these countries are occupied by others, and, to my knowledge, are less interested in Astronomy, one would probably do more harm than good, if one preferred these regions, however far south they are situated, to those farther north. On the contrary, as in winter, when nights are longer, it is possible to make observations more easily and on a larger scale, the northern regions have the advantage that they do not only offer this opportunity, but further, because of their sharp cold, particularly at a north wind, purify and rarefy the air to such a degree that it is often perfectly clean for several days running, so that the stars shine and twinkle at night to the highest degree, while at that time it is often raining in the more southerly regions, or the heavens at other times are overclouded and moist and less accessible to the observation of the celestial bodies. It is true that Prince Wilhelm, Landgrave of Hesse, etc., of glorious memory, who was highly interested in Astronomy, and was not a little initiated into it, encouraged me to settle in a more southerly place on earth in order to be able to watch the celestial bodies on a larger scale, as appears from a letter from him to me printed in the first volume of my astronomical letters p. 21 [Opera Omnia VI, p. 48-49]. And there is no doubt that he did so with the best intentions, and perhaps also to entice me to go there. But I am of opinion that no fewer observations    can be made in Denmark than in Hesse or any other part of Germany, to say nothing of other European countries, apart from the fact that in the more southerly regions some stars appear which are always hidden in the north. This is not, however, of particular importance and does not contribute very much to the redintegration of astronomy. This may be proved from the twenty-one manuscript books in my possession, which contain very accurate observations from as many years, all made in Denmark, so many and so good as I think nobody has hitherto provided in other places, even in more southerly regions, may my words not give offence! Here are found not only frequent and multitudinous investigations of all the places of the planets and their changing courses for each single year, even of Mercury, which appears more rarely as it retires very little from the sun; but also the positions of the fixed stars, in so far as they are in any way visible, have been recorded and on the basis of the notes entered in a catalogue of such a kind that it is impossible to find anybody, even among those who formerly lived in Egypt and the southern countries and the regions where the air is considered serener, who has performed anything like it, any more than any of their successors wherever they may be. I shall, God willing, soon prove that 1 do not tell all this out of arrogance or in contempt of the ancients in any way, but because I am in harmony with the truth.
So much for the choice of place, at which, however, I permit anybody to follow his own taste as he likes. Circumstances will offer other suggestions, and even if it is impossible to have all one�s wishes fulfilled, one must accept the facilities that offer themselves, so that one rather obtains something than nothing.
Further, the buildings ought to be so constructed that they may conveniently serve the observations and yield space for all the various instruments so that in accordance with their size and form they may be placed in a fixed position and in the right and proper manner. Further they should be protected against being damaged by the air, wind, and rain. Likewise, they must above the instruments themselves be provided with a roof, which, when necessary, can easily be opened and again closed. The material of which they are to be built, must be all stone, either bricks or other stones found in the soil, and if necessary the instruments must also, for the sake of safety, be supported by marble pillars or other stone pillars, and all must rest firmly on their base so that they cannot in any way shift, or in time come to rest less firmly. But the roof must be made of a more loosely joined material in order that it may be more easily opened and again closed. There must also be guardrooms and heating installations for those who are to assist these observers. And both this and the rest of the accessories ought to be arranged so practically that no trouble, no difficulty, and no inconvenience delays the work proper or makes it unpleasant.
But anybody who has the means, will at his discretion be able to devise and construct other forms of buildings for the purpose according to the opportunities of the place and the arrangement and number of the instruments. In this respect I am of opinion that I need not offer particular directions for anybody. But if anybody wants to know the procedure we have preferred and carried through in these building works, which have cost us so much trouble and so great expenditure, on this island of Venusia (in the vernacular called Hven) in the Danish Sound, which is visited by so many ships. (a work which was begun twenty-two years ago), I shall state it in order that the places and the arrangement of the buildings may be known in which the instruments depicted and described above have been erected. Anybody may take what he wants from this account and adapt it according to his needs. For I hope that also in future there will be some who are caught by such high interests and who will take great pains to imitate or even surpass these works.