Patents and plagiarism: Walker's Wire Strainer

Posted by John Pickard on

One of the basic tenets of patents is that an invention must be novel and not previously in the public domain. Despite this, a Tasmanian patent was granted for a direct copy of the most successful Australian wire strainer.

Walker’s Wire Strainer in Tasmania

On 4 August 1884 Charles Osbern Ralph Walker lodged patent application 330 in Tasmania for An improved wire strainer. It was one of his applications in each colony for his wire strainer that is still being manufactured and used over 130 years later.


(National Archives of Australia A1565-330)

Walker licensed William McLean (McLean Brothers and Rigg, 69 Elizabeth Street, Melbourne, Vic) the “sole and exclusive right to sell wire strainers constructed according to the said patented invention within the said Colony of Tasmania”.

(John C. Ferguson (1886) Daily Telegraph (Launceston) Saturday 24 April 1886, p. 4)

The strainer was advertised by agents and retailers in Tasmania in 1886 and 1887, and was imported from Melbourne in 1889. It was commended at shows of the Western Agricultural Association (Westbury) and the Northern Agricultural Society (Longford) in 1886 and 1887 respectively. So it was well-known across Tasmania.

Davidson and Brown’s strainer: plagiarism and no novelty

Ten years after Walker’s Tasmanian patent, Robert Lawrie Davidson and Richard Brown applied for a Tasmanian patent for An improved wire strainer on 3 October 1894, and Tasmanian patent 1,339 was granted.

The strainer was essentially identical to Walker’s: a cast-iron roller with shoulders and cross-holes for levers. The sole claim in their specification was for a “tubular barrel wire strainer” with shoulders. However, Walker’s Tasmanian patent specifically included tubular construction as an option: “wire strainers consisting of a roller either hollow or solid, …”

(National Archives of Australia A1565-1339)

Even a casual glance at the two patent diagrams shows that Davidson and Brown’s is a direct copy. Their perspective drawing of the strainers on a post is a breath-taking example of plagiarism.

Given the popularity of Walker’s strainers, and that Walker’s Tasmanian patent still had four years to run, there was certainly no novelty in their “invention”. And Davidson and Brown must have known about Walker's patent. So why was their patent granted?

The explanation lies in the Tasmanian patent legislation

The Patents, Designs, and Trade Marks Act 1893 (Tas) had no requirement for the Patent Office to assess the novelty of an application. Provided an application was in the correct format, it was accepted, and a patent granted.

However, the legislation allowed objections to an application; and an aggrieved patentee could petition for revocation of an infringing patent on the grounds of falsely claiming to be the first inventor. A licensee or manufacturer of the original infringed patent could also petition for revocation.

Despite this, neither Walker nor William McLean, his licensee in Tasmania, objected to Davidson and Brown’s patent application or petitioned for its revocation.

The outcome

Tubular versions of Walker's strainer were manufactured, but today they are very rare in collections. None has been recorded from Tasmania. Perhaps they were not strong enough and broke during straining.

In the event, Davidson and Brown never advertised their strainer. Perhaps McLean sent a “cease-and-desist” letter. We will probably never know for sure, so it remains a minor mystery of Australian rural fencing.

 Further information

Read more about the success of Walker’s Wire Strainer in Australian Wire Strainers published by Australian Fence Publishing. You can order a copy at the following link:

Buy Australian Wire Strainers | Paperback Edition.


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