Mr. Sci Science Factory Kala Pocket Sundial

I am a tour guide at Housesteads Fort on Hadrians Wall and wanted something to use, if the opportunity arose, to illustrate the kind of technology the Roman Army on the wall might have had at it's disposal. I could not find anything precisely right, with this device being the nearest I can get to what I was after.I am most impressed with the quality of the device, it is well made, the engraving is (to my old eyes) excellent. It all depends of course on what you want to buy this for (me being an amatuer in the scientific instrument world)#), but for me it is well worth the expense. As a consequence I have also bought one of the "nocturnals" from the same company and will be using it for much the same reason.As a by the by, though it is small, the packaging it comes in (a cork pad providing backing), is also very good in my opinion. Delivery was well executed too. All in all a good purchase for me.And having learned how to use it…. It does work. Neat.

Una pieza de colección!

I've been collecting and making portable sundials for 25 years, but in the back of my mind I always wanted one like this. (I have a home-made one that my husband made, and it's actually more accurate and easier to read, but it's not historical. It has a rubber washer for the gnomon and paper scales glue to the brass and I love it. But I've always kind of wanted a replica of a historical one.)This one is a replica of one I saw in a book on the history of sundials all those years ago. I remember reading that George Washington carried one like this, maybe when he was a surveyor. I love how it's about the size and shape of a pocket watch.I have a little trouble getting the two rings to click into place at right angles, but with some pressure I can do it. It's also hard to read, with the spot of light on the inside of the ring and the markings in Roman numerals on the side in fairly small print. But the engraved brass is beautiful. It's also kind of magical seeing that spot of light appear on the ring.My only tiny complaint is about the instruction booklet. I think it needs a little extra information. While it's true that this type of dial also works as a compass, showing you where north is (or south if you're in the southern hemisphere,) that only works if you know whether it's morning or afternoon. If it's 9 AM, the sun is at the same altitude as at 3 PM. You can get the spot of light to shine on the dial at 9 AM and the bar will be pointing north, but you can also orient it differently and get it to shine at the place where it says 3 PM. At that second orientation it will not be pointing north.Also, if you really want to use this to tell time, do some reading about the Equation of Time and how time zones affect local time. Because the earth's orbit is an ellipse, any sundial will disagree with clock time by up to 16 minutes at certain times of the year. And if you don't live near the center of your time zone, you could be off by as much as half an hour or even more and have to adjust for longitude. And then there's Daylight Savings. None of that is a fault of the sundial. You could say that it tells the real time and it's the clocks that are off.

Perfect addition to my sunroom! Very intricate writing and very well made. Thanks for the quick delivery and I am very pleased with the purchase.

Excelente construcción, al principio es un poco complicado de leer la hora, pero es óptima para usar en cualquier latitud del mundo. Recomendable.

Accurate to the MINUTE, however, this gives you local SOLAR time, not STANDARD (clock) time.... something very easily accounted for if you know what to do: add one hour if you are in a region that acknowledge Daylight Savings Time (DST) AND you are in DST period. If you are NOT in DST period, and instead are in Standard Time period, do nothing. Then add or subtract however much time is needed to correct for your longitude. However, this is very common with sundial. Then you CAN correct for the Equation of Time (EOT), but it isn't totally necessary as it can only be off by 16 minutes or less, depending on the time of year. They do sell brass sundials that "automatically" correct for these 3 discrepancies... IF you want to fork out $8,000 or more for one. The only other "problem" is during the equinoxes, the center ring prevents the dot from being cast onto the outer ring. This can also be accounted for in a minute or 2 with some "fiddling around" which I will not get into here as it would require a lengthy explanation. Read a book on understanding how sundials work if that's a concern to you. The only real concern I have with this is that the adjustable monthly slide and the adjustable ring that wraps around the outer ring are steel and not brass. Will they rust? Idk. If they do, I'll consider taking to a jeweler and setting if they can be replaced with brass and if it's worth the cost. If so, I'll try to remember to come back here and update. Again, this IS a highly accurate universal equatorial ring dial and well worth the [roughly] $60 it cost. Most major complaints are either pretty irrelevant or due to operator error/no understanding of how these work. 5 stars.