Fitzroy Storm Glass





Introduction: Fitzroy Storm Glass

This instructable will take you through the steps of making a Fitzroy Storm Glass.

Fitzroy's Storm Glass - Weather Instrument Used on Darwin's Ship the HMS Beagle
Admiral Fitzroy (1805-1865), as commander of HMS Beagle, participated in the Darwin Expedition from 1834-1836. In addition to his naval career, Fitzroy did pioneer work in the field of meteorology. The Beagle's instrumentation for the Darwin Expedition included several chronometers as well as barometers, which Fitzroy used for weather forecasting. The Darwin Expedition also was the first voyage under sailing orders that the Beaufort wind scale be used for wind observations. One type of barometer used by Fitzroy was a storm glass. Observing the liquid in the storm glass was supposed to indicate changes in the weather. If the liquid in the glass was clear, the weather would be bright and clear. If the liquid was cloudy, the weather would be cloudy as well, perhaps with precipitation. If there were small dots in the liquid, humid or foggy weather could be expected. A cloudy glass with small stars indicated thunderstorms. If the liquid contained small stars on sunny winter days, then snow was coming. If there were large flakes throughout the liquid, it would be overcast in temperate seasons or snowy in the winter. Crystals at the bottom indicated frost. Threads near the top meant it would be windy.

Step 1: Equipment

You will need a glass container that is seal-able. ( I used an old 100ml measuring tube and cork)
A piece of appropriately sized wood for the base. ( I used a piece of 70x70x40 Iroko)
Epoxy Glue to bond the glass to the base.
Lathe, Turning Tools and finishes
Printer and laminator to make info cards.
2 Beakers to mix chemicals in
Chemicals to make the storm glass contents are:
2.5 g potassium nitrate
2.5 g ammonium chloride
33 mL distilled water
40 mL ethanol
10 g camphor (natural not synthetic)

Step 2: Making the Storm Glass Content

Please take care when handling chemicals and wear PPE
  1. Dissolve the nitrate and ammonium chloride in the water in beaker 1
  2. Dissolve the camphor in the ethanol in beaker 2
  3. Slowly mix the two solutions beaker 1 into beaker 2
  4. Place beaker 2 in some warm water and stir until everything is fully mixed.
  5. Decant into your storm glass tube and seal.
It will take a possibly several hours depending in the current weather for anything to happen to the liquid.

Step 3: Making the Base

The base was turned on the lathe. Take you piece of wood and drill and 8mm hole* and mount on a screw chuck. Then using a fostner bit in the tail stock drill a 30mm* hole 10mm deep into the centre of your wood. Open up this hole using a flat ended box scraper so your glassware is a snug fit (not too tight as space is needed for glue). Now turn the outside shape, first using a spindle roughing gouge followed but a spindle gouge to introduce a pleasing shape. Then sand to 400 grit. I chose to embellish with two burnt lines by putting two v-grooves in using a skew chisel and then using thin wire create the burn mark. Another light sand to clean up the burnt line edges and then apply sealer and hard wax. Sand bottom flat once removed from lathe

*Sizes relavent to my equipment, please adjust for your own

Step 4: Final Assembly

Glue the glass tube into the wooden base using epoxy glue.

I then made little cards explaining what a storm glass is and what the different crystal structures mean.

The cards contain the following text:

Fitzroy Storm Glass
Admiral Robert Fitzroy was Captain of the HMS Beagle, the very same ship that ferried Charles Darwin around the Galapagos in the 1830′s. 

While Darwin contemplated the origin of the species, Admiral Fitzroy was testing an hypothesis of his own.  He was testing a new weather predicting instrument.

In a sealed glass, he mixed potassium nitrate, ammonium chloride, ethanol, camphor and water, and created the storm glass. Admiral Fitzroy observations were thus:

-If the liquid in the glass is clear, the weather will be bright and clear.
-If the liquid is cloudy, the weather will be cloudy as well, perhaps with precipitation.
-If there are small dots in the liquid, humid or foggy weather can be expected.
-A cloudy glass with small stars indicates thunderstorms.
-If the liquid contains small stars on sunny winter days, then snow is coming.
-If there are large flakes throughout the liquid, it will be overcast in temperate seasons or snowy in the winter.
-If there are crystals at the bottom, this indicates frost.
-If there are threads near the top, it will be windy.

 The PDF attached has the cards properly formated



  • Pocket-Sized Contest

    Pocket-Sized Contest
  • Pro Tips Challenge

    Pro Tips Challenge
  • Paper Contest 2018

    Paper Contest 2018

We have a be nice policy.
Please be positive and constructive.




Does denatured ethanol work or does it need to be lab grade? I made one with 100 proof vodka but want to see if they react differently.

It should work, it may depend a little on what has been introduced to it to make it not drinkable (impure) .

You may be astonished, as I was, to learn that the only chemical necessary for this is camphor. The other chemicals have no effect on its operation. I learned this from this study:

The chemical weather glass: composition and operation—Allan Mills. Department of Geology,. University of Leicester


He did a study of the composition trying just the other two chemicals, all 3, and just camphor. He found the other two chemicals alone did nothing, and camphor alone worked just as well as all 3 chemicals together.

This has to be set outdoors for it to work. See Customer Reviews: Lily's Home Admiral Fitzroy Storm Glass.

For all those saying it "Just sits there"

ByJayon December 18, 2013

The Fitzroy Stormglass was intended to be used outdoors when invented. Leaving it inside in controlled conditions, well, you get no changes, because "nothing changed!"

Since temperature is the only thing that affects the crystallization, this makes perfect sense.

Where can I get pure ethanol?

You can't because it would absorb water from the air as soon as it was made. The closest thing you can get is 95% ethanol—Everclear. It is very expensive. A cheaper solution is to use 100 proof cheap vodka. It is 50% ethanol. The required concentration is 40/(40+33) = 52%, so 50% is more than close enough for something like this. You would measure out 77ml of vodka for this formula.

sorry only just seen this, were in the world are you? you can get it on both eBay and Amazon in the UK

thank you a lot fo your article

am i interpreting the storm glasses in your intro picture correctly ? frosty and windy day