How effective is the ‘Coolgardie safe’?

10 Friday Feb 2017

Posted by Jacqui Durrant in Eldorado, Low tech, Uncategorized, Wangaratta

Tags

Coolgardie safe, Eldorado Museum, meat safe

I’d read many positive testimonials in relation to the legendary pre-electric cold-store unit, the Coolgardie safe… but I still wondered how well did it really work? When curiosity finally got the better of me, the Eldorado Museum Association came to my aid with the genuine article.

Coolgardie safe, courtesy Eldorado Museum, Victoria

In my first post of 2017, I’m going to momentarily diverge from the 1850s gold rush. Meanwhile, I hear you asking, ‘What is the Coolgardie safe?’ The short answer is ‘a meat safe’ — but there’s more to it than the Coolgardie safe being a ventilated, vermin-proof box in which to store perishable food.

The Coolgardie safe was invented in the 1890s on the goldfields of Coolgardie, Western Australia, by Arthur McCormick. McCormick had observed that a wet bag placed over a bottle cooled its contents, and that if this bottle was placed in a breeze, the bag would dry out more quickly, but the bottle would get colder. What he was observing was the basic principle of heat transfer that occurs during the process of evaporation: that as it transforms from a liquid to gaseous state, water consumes energy in the form of heat, taken from its surroundings. [1]

Designed to take advantage of the cooling effects of heat transfer from evaporation, the Coolgardie safe was a common household item in Australia until the mid-twentieth century, initially vying with iceboxes until finally overtaken by kerosene and electrical fridges. I’d read many descriptions and testimonials regarding the Coolgardie safe, but I still wondered if it worked, and if so — how well?

I knew that the Eldorado Museum had one in its collection [2], which, until recently, had languished ‘out the back’ until local Howard Phillips gave it a fresh jacket of hessian so that it could go on display. Once on display, members of the Ross family from Wangaratta recognised it as a model that had been manufactured by their family business in Wangaratta (albeit more than half a century ago), and so they donated a set of brass name plates to attach to it. It was my good fortune that the Eldorado Museum Association agreed to let me borrow this safe for a living history trial.

Manufacturing plate on the Coolgardie safe at the Eldorado Museum.

This particular Coolgardie safe is of a common type: a rectangular metal frame, which supports hessian sides, wired on. It has a simple hinged door on the front, and one internal shelf. The top of the frame has a galvanised sheet-metal tray (ie: a reservoir), which is filled with water. Strips of flannel are hung from the tray to contact with the hessian sides, which keeps them damp through a process of capillary siphoning (wicking). When a breeze comes, it passes through the wet hessian and evaporates the water. This cools the air inside the safe, and in turn, cools the food stored inside. The drier the air is, the greater the rate of evaporation, and the cooler the safe. The feet of the safe sit in a tray of water (also on legs), which acts as a moat to keep ants at bay, and collect water dripping from the hessian. Sometimes these trays had a tap to drain the water, but this model has only a simple spout. There is also a central vent in the bottom of the safe which vents through a little chimney passing through the middle of the reservoir at the top — and I’ve seen other Coolgardies with this feature.

Another Coolgardie safe complete with a lid over the water reservoir. This safe has had wire mesh added at a later date (probably for decorative effect) where the hessian panels would have sat. (Photo swiped a long time ago from a seller on eBay!)

Day 1, 9 February 2017

I put the safe under my back verandah and filled the reservoir to the very top, which really kicked-off the wicking process: water could be seen wicking from the flannel down and across the hessian panels in a matter of seconds. Initially the strips of flannel I used were only half the width of each hessian panel. To increase the amount of water wicking through the hessian, I doubled the flannels until they were virtually equal to the hessian panels. This optimised the wicking, and the safe began dripping continually from the bottom, as water ran off. Immediately, I could see why it would be necessary to have a drip-tray — simply to conserve and recycle water. (Ideally you would find an economic balance between enough wicking to make the safe functional, while preventing too speedy a loss of water from the reservoir.)

The water reservoir at the top is filled, and strips of flannel are draped over the sides to contact with the hessian panels.

After the reservoir was filled to the brim and the sides were wet, at 12.56pm, it was 30.5ºC in the shade of the verandah and 28.6ºC inside the safe, rendering a difference of 1.9ºC in temperature. (The thermometer I used was highly sensitive and constantly went up and down as much as 0.2ºC, and what’s more it read different temperatures under different places around the verandah, so my readings are a little rough.) I continued to monitor the temperatures, with these results (contrasting the temperature under the verandah with the temperature inside the Coolgardie safe, showing the difference between the two):

1.23pm — 29.6ºC vs 28ºC = 1.6ºC
1.32pm — 29.2ºC vs 26.4ºC = 2.8ºC
2.15pm — 32.3ºC vs 29.6ºC = 2.7ºC
2.42pm — 28.9ºC vs 25.6ºC = 3.3ºC

Perhaps the temperature would have continued to drop, but I decided to add a large pedestal fan to see if this would increase the rate of evaporation, and thus decrease the temperature. The short answer is, yes, it did.

3pm — 31.4ºC vs 26.4ºC = 5ºC
3.22pm — 33.6ºC vs 28.5ºC = 5.1 (and this temperature steadily fell…)
3.39pm — temperature inside dropping to 25.2ºC
3.42pm — 32.6ºC vs 24.7ºC (and my guess is, still dropping) = 7.9ºC

So I could say that the Coolgardie safe, when wicking steadily, ran from a bit over 2.5ºC to 3ºC cooler than the outside temperature, and between 5ºC to perhaps as much as 8ºC cooler when there’s a decent (albeit artificial) breeze.

Frankly, I don’t consider these to be amazing results. However, this was all without the drip tray beneath the safe. The drip-tray that came with the safe was rusted-through, so I hadn’t used it; but now I was beginning to wonder whether the tray may have also provided some micro-climatic benefits.

This question is something I’ve decided to pursue on the ‘morrow. As I write this, I’m about the pull a beer, chilled to 4ºC, from my fridge.

Day 2, 10 February 2017

I didn’t get started until later in the day, and it was a scorcher, topping a bit over 39ºC! This time I put the drip tray under the Coolgardie safe, and filled both it and the reservoir at the top. I didn’t use the fan at all. The results speak for themselves:

At 3.15pm it was 39.1ºC degrees in the sun, 36.9ºC under the verandah, and immediately 31.4ºC in the Coolgardie. This dropped to 30.3ºC within the next ten minutes.

Here are some readings:

3.15pm — 36.9ºC vs 30.3ºC = 6.6ºC
3.45pm — 35ºC vs 26.1ºC = 8.9ºC
4pm — 34ºC vs 27.8ºC = 6.2ºC

Now I could say that when fully set up, the safe is at least 6ºC cooler and maybe as much as 8-9ºC cooler than the shade of the verandah. These are the best results I could achieve on a very, very hot day, without the aid of a fan. I admit this wasn’t the most scientific trial, and maybe there are other ways to achieve better results. If you have any ideas, please let me know.

Thanks to my sponsors, the Eldorado Museum. This is the second living history trial in which I have been ‘enabled’ by members of the Eldorado Museum Association and other friends from Eldorado. The first trial was the manufacture and use of a replica gold cradle based on one held in the Museum’s collection. You can read about that here.

[1] In my history of the Coolgardie safe, you may recognise information swiped from the Powerhouse Museum and Museum of Victoria.
[2] Indeed, there are very few domestic household items from the mid to late nineteenth century that the Eldorado Museum doesn’t have in its collection!

How the gold was won: mining on Spring Creek, 1852.

29 Thursday Dec 2016

Posted by Jacqui Durrant in Beechworth, Californian gold rush, Gold mining, Gold rush, Ovens diggings, Spring Creek diggings, Uncategorized

≈ 5 Comments

Tags

Californian sluice, gold cradle, Long Tom, Whip, Windlass

This blog post presents an eye-witness account of how gold was mined on Spring Creek (Beechworth) in the rush of 1852. If you want to know why the image of the solitary miner gently panning for gold by the side of the creek is a fallacy… read on.

WARNING: This is a monumentally long post. It is broken into headings, to facilitate skim reading and promote a modicum of sanity.

Note: this post is about mining on Spring Creek, which is now referred to on some maps as ‘Silver Creek’, and runs through the modern town of Beechworth.

As I said in my last post, one of the most exciting things about the gold rushes of the 1850s was that anyone with a small amount of capital and a few friends or acquaintances, could stake a claim and mine gold using basic equipment — the design of which had been refined on the Californian goldfields only a few year previous.

By far the best eye-witness account I’ve read of the activity of gold mining during the Beechworth gold rush was written by Edward Ridpath [1], who arrived on the Spring Creek diggings on 4 November 1852. At this point, the diggings were still quite fresh: Ridpath says he was ‘much surprised at their general appearance… that their operations were confined to a spot of ground about one mile in length, and about a hundred yards in breadth…’

An early drawing of the Spring Creek diggings around December 1852, by Edward LaTrobe Bateman. This view is taken from southern side of the Creek looking towards the Commissioner’s Camp, which was situated where the Police Station and Gaol are today (Image: State Library of NSW).

Alluvial mining

The mining on Spring Creek was ‘alluvial’ — meaning that gold was found in deposits of sand, gravel and soil that had been washed and transported by water. ‘[T]here are two sources whence gold is derived,’ Ridpath tells us, ‘one from the bed of running creeks, the other from the earth’.

Thus, at Spring Creek in early November, Ridpath noted, ‘the first parties that arrived here worked a bed of the creek which had proved uncommonly rich and well rewarded the adventurous discoverers, [and] the soil adjoining was now being tried…’ [2] By the time another Englishman, William Howitt, arrived in mid-December, ‘The creek, that is, a considerable brook, was diverted from its course; and all the bed of the old course was dug up.’

Staking a claim, sinking a shaft

To dig for gold along Spring Creek, Ridpath explained,

the preliminary step is to sink a shaft, which in these diggings varies from 6 feet to 46 feet in depth [i.e.: 1.8-14 metres] according to the nature of the surface, the shape of the shaft is according to the fancy of the digger, whether round, oval, square or oblong, the first is the most used, before sinking, he first marks out by a trench his claim, or ground he is entitled to, consisting of 12 ft square every way, then commences working with a pick and shovel, throwing the dirt up to the surface after picking it, till he obtains a depth of 7 or 8 feet.

Miners had to work their 12 ft square claim constantly, or else their claim was forfeited.

Using a windlass or whip

Once a depth of 7 or 8 feet was reached, ‘a wooden windlass is fixed, [and] the dirt is then pulled into buckets and hauled up.’ A windlass was a structure mounted over the shaft, fitted with a hand-cranked winch, which Howitt explained, was ‘rudely constructed out of the wood that grows about.’ Some miners preferred instead a structure containing a pulley mounted over a shaft, or even more simply, a pole centrally counter-balanced on a forked stick set into the ground, with the bucket attached by rope to one end, known as a ‘whip’.

Illustration of a windlass: ‘Edmond Armand, Chinaman’s gully, 23 November 1853’, which appears in A pioneer of the fifties: leaves from the journal of an Australian Digger, 18 August 1852-16 March 1854, drawn by Eugen von Guerard (Image: State Library NSW).

Finding the ‘washing stuff’

The shaft was dug until the miners hit the layer of wash dirt containing the gold, which Ridpath explains, was found just above

…the rock or pipe clay, the former consists of granite, sandstone, and slate, either rotten or hard, the stratum of earth that lies on this contains (if there is any at all) the gold, the depth of this stratum varies from 6 inches to 7 feet, the latter very rarely, sometimes a stiff clay extends down to the rock, in which no gold is ever found, the technical term for this stratum is washing stuff, its chief colours are red and white, it is strange that although the dirt above this should be free from any hard substance, this is mixed up with pebbles from the size of pin heads to that of a bullock’s, they are of all shapes…

Working the claim

Once the layer of wash dirt was found

…on coming to the rock the digger takes a tin dish full of the washing stuff to try and see if it will pay for his labours in working the whole claim… if, as I said before, there is any encouraging promise, he begins to make a tunnel with a small sharp pointed pick, from the shaft to the boundary of his claim, about four feet wide and three feet in height necessitating him of course to sit like a tailor all the time, this is continued all round the claim in order to secure it from encroachments of his neighbours who will always take advantage of less able work-men than themselves, after this is completed, the rest of the ground is picked away and supported by wooden pillars so that there is a complete excavation, as this is the case with all the claims on the diggings where the ground is good, you might crawl under it for several hundred yards with few interruptions, very much like a rabbit warren, candles are always used in the tunnelling; as the stuff is picked, it is shovelled forward to the shaft, put into buckets, and hauled up…

In deep claims being worked by candle-light, the air would be foul, so ventilation was provided by ‘a windsail, like those aboard emigrant ships, to carry down fresh air.’ This device was simply a sail terminating in a long canvas pipe, rigged to catch and direct breezes.

Howitt tells us that ‘The diggers themselves generally ascended and descended by a rope fastened to a post above, and by holes for their feet in the side of the pit.’

Washing the wash dirt

Once the claim had been worked out, with all the wash dirt containing gold brought to the surface and put aside, this was

either carted down to the creek or washed near the shaft, from a water hole, by the latter method, although the expense of carting is saved, yet the thickness of the water carries away the fine gold; before being washed in the cradle it is first thoroughly puddled or moistened in a long trough or common washing tub!

Ridpath also notes that the gold mined from the creek bed was ‘very easily sought, requiring only to be shovelled once into the cradle, to be washed,’ (i.e.: no puddling was required.)

Once the earth had been ‘puddled’, and the hard lumps had been dissolved, the gold was roughly separated from the wash dirt using one of three devices:

Gold Cradle, aka Rocker.

The gold cradle was both cheap and portable, making it the most common gross method of separating the gold from wash dirt in the early days of the gold rush. As Ridpath offers, ‘perhaps you are already acquainted with this machine, one could have no clear notion of it, unless it is seen illustrated’.

I detail the use of this ‘machine’ with photos in an earlier post, Cradling for Gold in the Woolshed Valley.

Cradling by S. T. Gill (Image: State Library of Victoria)

Long Tom

The second most common piece of equipment was the ‘Long Tom’, often shortened to ‘Tom’:

…there are two other machines on a more expensive scale used for washing gold, both Californian in origin, one is called a Long Tom, averaging 5 feet in length, /2 feet in breadth and half that in height, this is always fixed in a creek, so that there is always a stream of water running through it, the washing stuff is put into this, then shovelled backwards and forwards till it is thoroughly moistened, when the gold is carried down by the force of the stream to the other end through perforated sheet iron (to prevent the stones mixing with the finer dirt) into ripple box whence it is taken out and cleaned in a tin dish…

The ‘ripple box’ was a false bottom on the Long Tom, which was fitted with riffles — bars or cleats which would catch the heavier gold while the flowing water washed the lighter material away. (‘Ripples’ was the Australian term for ‘riffles’.)

Californian Sluice

Whereas Long Toms were essentially portable sluice boxes,

the other machine is a sluice, shaped like a Long Tom, but considerably longer, unlike the latter, the water is conveyed from a distance by means of a hose, the length of the sluice is about sixty feet sometimes less, it is usual for about two or three parties to own them, and to employ men to work them at the rate of one pound per day, their being able to wash so much stuff during the day enables them to make the rejected stuff of others profitable, who cannot get through so much in the same time, there was no sluice erected on this creek, until it was abandoned by everyone else’.

there was no sluice erected on this creek, until it was abandoned by everyone else

Washing the gold in a tin dish (gold pan)

The final step in the process was to take whatever remained in the the bottom of the Cradle, or caught in the ripples of the Long Tom or Californian sluice, and wash this in a tin dish, gently removing any heavier material that wasn’t gold (commonly tin dioxide, aka ‘black sand’). Then all that remained was to weigh the gold and divide the proceeds between the party.

The process of mining gold on Spring Creek was relatively simple compared to that on diggings known as Reid’s Creek — downstream from the Spring Creek diggings, about 4 miles distant. The Reid’s Creek diggings presented more arduous and complicated prospects for miners (which arguably also made them a grumpy and rebellious lot), for reasons I will detail in the next post. I promise it will be shorter.

Notes

1. All the quotes in this article come from between pages 9-16 of Edward Ridpath’s journal: Edward Ridpath, Journal, transcription of letters to his father, possibly in his own hand, 1850-53? [manuscript MS 8759], State Library of Victoria, Box 1012/4 [Box also includes his gold license from 3 August 1853], except where I have noted that they come from William Howitt, in which case they have been drawn from Chapter 10 of Land, Labour and Gold (1855).

A useful document when considering nineteenth century gold mining technologies is:
NEVILLE A. RITCHIE AND RAY HOOKER, ‘An Archaeologist’s Guide to Mining Terminology‘, AUSTRALASIAN HISTORICAL ARCHAEOLOGY, Vol 15, 1997, pp:3-29.

Stuff that has nothing to do with the gold rush (which you might think does).

26 Monday Dec 2016

Posted by Jacqui Durrant in Beechworth, Eldorado, Gold mining, Gold rush, Uncategorized, Woolshed Valley, Yackandandah

≈ 2 Comments

Tags

Cock's Pioneer Dredge, Eldorado gold dredge, Lake Sambell, Rocky Mountain Gold Sluicing Company, Stamp Battery, Wallaby Mine

When most of us think of how gold was mined ‘in the olden days’, we think of a solitary miner washing dirt in his gold pan by the side of a creek. After that, the confusion and mythology sets in. In order to help simplify matters, this week’s post presents a list of mining methods and equipment NOT used during the Spring Creek and Reid’s Creek (Beechworth) gold rushes.

12 Head Stamp Battery at the Wallaby Mine (Image: Heritage Victoria)

Yes, I’m a grumpy historian. I get really annoyed when people ‘conflate’ (combine) different historical periods into one. The Victorian gold rushes are often conflated with later periods of gold mining, but the reality is that the major gold rushes of the era (which took place in Ballarat, Bendigo and Beechworth districts) belonged to a short period of time (1851-53), in which people used particular equipment and had a particular mind-set.

One of the most exciting and attractive things about the gold rushes of the 1850s was that anyone with a small amount of capital and a few friends or acquaintances, could stake a claim and mine gold using basic equipment. Contrary to popular belief at the time, gold wasn’t easily-won (it involved hard labour), but the great virtue of the gold rushes was that anyone with a reasonably strong physical constitution could become a ‘gold seeker’. At the height of the Spring Creek and Reid’s Creek gold rushes, which took place over a few months in the late Spring and Summer of 1852-53, no large scale mining equipment was used.

So here are some mining techniques and equipment that had nothing to do with the gold rushes:

Hard Rock Mining / Stamp Batteries — Hard rock mining did not begin in the Beechworth/Yackandandah area until all the (comparatively) easily-won alluvial gold was exhausted. The gold bearing quartz was crushed using stamp batteries. There’s a massive stamp battery at the Wallaby Mine, restored after the 2003 bushfires by Parks Victoria. There are other stamp batteries to be seen at Myrtleford and Bright. (Picture above.)

Gold Dredging — Gold dredges were used to dredge gold-bearing sands from creek and river beds, and process them. There’s a spectacular ‘bucket’ dredge at Eldorado. If you haven’t done so already, I suggest you go see it; and remember, this machine began operating in 1936, long after the gold rush had finished.

Cock’s Pioneer Dredge at Eldorado, commenced 1936 (Image: Peterdownunder)

Open-cut sluicing — Some large open-cut mines existed in the Beechworth and Eldorado areas, in which gold bearing soils were broken down for processing, using high-powered hoses. The ‘clay banks’ on the side of Lake Sambell in Beechworth are the visible remains of one such open-cut mine, run by the Rocky Mountain Gold Sluicing Co, which formed in 1867. The pit which became Lake Sambell was the result of large-scale company mining, which started (in this case) 15 years after the gold rush.

Pine trees growing on the exposed ‘clay banks’ left by gold sluicing operations, on the side of Lake Sambell, Beechworth (Image: Jacqui Durrant)

Other forms of mining and gold processing that came much later than the initial gold rushes include Deep Lead Mining (which happened at Chiltern, and at Rutherglen where there was no hard rock mining, but mining of alluvial material found deep underground), and gold processing using cyanide (which happened at Chiltern).

In the next post, I will return to the 1850s and talk about how gold was mined during in the gold rushes, considering the different conditions on the Spring Creek and Reid’s Creek diggings. And I will be less grumpy.

Life on Spring Creek

Category Archives: Uncategorized

How effective is the ‘Coolgardie safe’?

How the gold was won: mining on Spring Creek, 1852.

Stuff that has nothing to do with the gold rush (which you might think does).

More problems with poo: an up-date on last week’s blog post.