Waldemar

I also calculated the weight of this barrel for possible verification of its dimensions. Reading the engraved weight markings as ‘XVI S(keppund) : X L(ispund) : [...] Markpund’ gives a result of approximately 2250 kg. Admittedly, this is a fairly typical weight for a legitimate 24-pound cannon, yet this particular specimen, as a ‘drake’, is a relatively light cannon, being short and with thin barrel walls, so the result seems quite reliable. Now, if you make a 3D model of this cannon (or even without it), you can calculate its volume and multiply it by the specific weight of bronze, which for a copper to tin ratio of 10:1 should be, say, between 8.5 and 8.6 g/cm³. This is actually the least reliable component of the calculation, as the actual alloy may have had different proportions and also other components as well. But these calculations are not difficult and are always worth doing in similar reconstructions.

Again, Swedish digitaltmuseum, and again I am not able to provide a link for this specific plate, which I did not written anywhere when downloading, sorry. It must come from the Armémuseum resources.

@TJM I think I have found a drawing of the Danish 36-pound cannon from the period of Christian IV that you are looking for. It is a chambered cannon, also known as a ‘drake’. Admittedly, the drawing does say 42 pounds, but it is a Swedish made drawing, and in Swedish artillery of that period, calibre was given in skålpund, which was 0.425 kg. When converted to Danish pounds (0.5 kg), this gives a calibre of 36 pounds. As in Thelott's drawings, the „scale” is a just gun's calibre divided into 24 parts, so you will have to find the overall size of the barrel by referencing to the known diameter of the gun's bore.

Hi Matthias, In theory, it seems to be a good idea, but I know that in practice, museum staff treat such queries as a nuisance. However, it's not even a great pity, because they are usually only able to answer questions of a standard level of knowledge, so to speak. I wish I were wrong, but I know personally a number of museum employees...

Okay, I hope you will sort these issues out one way or another. Maybe I will also benefit somehow when you discover some pattern that will make it easier to recognise the original size of the cannons. Just one thing that makes it somewhat easier is that, unlike the copies downloaded directly from the Armémuseum, the copies available at digitaltmuseum have scales calibrated in centimetres on the scans, so at least the size of the drawings is known.

Ah, these supposed scales do not show absolute units of length, but rather a gun's calibre divided into 24 smaller parts, because barrels, and especially their small elements such as the thickness and width of the rings and other decorative elements, were designed and measured proportionally in these submultiples of the calibre. This is precisely the problem with Thelott's drawings, that these ‘scales’ do not facilitate identification at all and even the estimation of size. In these circumstances, it will probably not be helpful that the Swedish foot is 297 mm, divided into 12 inches. ... and Thelott just arbitrarily scaled the drawings to fit the available space on paper.

To be on the safe side, I would like to add that many gun barrels have their weights engraved in the Swedish system, which can also be very useful in identifying the size and calibre of these specimens. This is in Roman numerals, skeppund : lispund : markpund, separated by a ‘:’, in proportions of 400 : 20 : 1, or metrically 136 kg : 6.8 kg : 0.34 kg.

Oh, I have one request for you, but only if it is not too much trouble. After identifying the Danish specimens in Thelott's drawings, would you please send me a list of them by volume and plate number? I would like to mark them as such in my copies.

Good luck!

My goodness, I can't find the right link to the Armémuseum archive in Stockholm right now, where one can download all three complete volumes of this collection at once. However, to offer something quickly, here is a link to digitaltmuseum.se, where you can download or view Thelott's drawings individually, plate by plate (it seems that they are all or almost all there, over 450 – mainly Russian, Danish, German, Polish, Lithuanian etc., and perhaps even a few from the times of Teutonic Order ). https://digitaltmuseum.se/search?q=philip thelott&owner=S-AM&o=0&n=50 The descriptions of the individual plates in digitaltmuseum also include library references. The plates are roughly grouped by country, but there is also some chaos, so it is worth looking through the whole collection. To identify the origin of a gun barrel, one need to look primarily at the coats of arms and inscriptions. If you want, I will continue to search for links to download these three albums in bulk. Below is an example of a typical plate, depicting a Danish cannon cast in 1613, i.e. from the period of the reign of Christian IV (or IIII, as it is written on this barrel ).

Oh, I almost forgot. A large number of Danish cannons can also be found in Philip Thelott's enormous collection from around 1700, which contains many hundreds of captured cannons from all neighbouring countries. A copy is also available online in the Swedish archives. However, Thelott's collection is not as well organised as Grunth's, in fact there are no descriptions, only drawings, without even calibres or sizes, and everything has to be deduced from the proportions of the cannons, their styling and the inscriptions on them.

Perfect! Many thanks again ! The 1860 edition is a wonderful addition, because monochrome mode can also be useful in some applications. And yes, indeed, I saw those few rare reproductions from Grunth's work in Niels Probst's publication on Christian IV's fleet, which I have in my home library, as well as some others from the same series, and still a few others on the Danish fleet. Among Danish authors, Probst is one of the most valuable to me, because he does and shows things that interest me the most, and yet from my favourite period .

Many, many thanks for your initiative in scanning this work and sharing the link to the scan. I have been searching for a copy of it for literally decades, without success until now. I was only vaguely familiar with its content thanks to a few reproductions in other publications. Once again, many thanks!

A pleasure to watch. And, once again, my favourite ‘mono’ colour scheme in muted tones .

I will start from the beginning, as it may be useful to others as well. To generate hollowing/bottom curves, Turesen constructed a separate progressive scale, specifically using a mathematical progression (in this case +2). Based on this, he built triangle ‘A’ (on the right of the below reproduction), which triangle was particularly useful in manual drawing for quickly scaling this linear scale. Fortunately, in a separate diagram (on the left of the below reproduction), Turesen has also shown how he used this progressive scale to generate the hollowing/bottom curve for the fashion piece. All that is needed is to adjust the progressive scale to both defining arms of the curve by scaling and rotating it appropriately, then, starting from the points on both scales, draw two sets of lines parallel to both arms, and finally connect the points where these lines intersect. And, voilà, the hollowing/bottom curve is ready . In order to maintain geometric consistency and, consequently, to obtain harmonious, smooth shapes, the same procedure and the same progressive scale should be applied to all other frames. In addition, the vertices and terminating ends of both arms of the hollowing/bottom curves for all frames must necessarily lie on a curve with a harmoniously smooth course, preferably on a straight line in the ‘body plan’ projection. — The location of point ‘B’ is the spot where the curve of the fashion piece changes from convex to concave (which may be also said of the start of the hollowing/bottom curves for all other frames), and it is even marked by Turesen himself on his diagram as point ‘L’ (see above). — Point ‘C’ is the apex of both arms defining the hollowing/bottom curve of the fashion piece. — Points ‘A’ and ‘D’ (the latter is the apex of both arms defining the hollowing/bottom curve) were found in such a way that they meet the following conditions: the course of the hollowing/ bottom curve for the master frame is consistent with the course of this curve on the original plan, and, the resulting lines ‘AB’ and ‘DC’ must generate the correct shape (i.e. consistent with the original drawing) of the hollowing/bottom curves for all other frames. Finding these points “A” and ‘D’ is a fairly typical iterative operation based on trial and error fitting. — Point ‘E’ is the spot where the first bend connects to the keel assembly. In a sense, the geometric nature of this point is similar to point ‘C’. — Point ‘F’ is again an empirically found spot where the frame contour switches from convex (or straight) to concave form. As with the aft part of the hull, the resulting lines ‘DE’ and ‘AF’ must meet the conditions described above for lines “AB” and ‘DC’, i.e. they must correctly define the coordinates for the arms of the hollowing/bottom curves of all frames.