Manufacture of the typical barograph has been in production for almost 150 years and over the decades there have been numerous variations on the original design. The actual working mechanism has occasionally been altered for reasons of style, accuracy, economy etc. These variations became popular for short periods and then returned in favour of the traditional and more recognisable movement and, in fact, still used until all production of barographs in the UK ceased about 10 years ago.
One particular design variation which I believe was underrated is this ‘Spring’ Barograph. SIgned by reknowned English makers. J H Steward of The Strand, London, together with a 'patent applied for' plaque this extremely rare instrument has had a professionally repolished walnut case and will be of interest to specialist collectors.
 
A respected professor and colleague of mine comments...
‘In simple terms, the diaphragm stack is held apart by either a simple heavy weight or firmly anchored with a sturdy spring allowing the minute flexing of the stack to be transmitted on the recording chart - even with the smallest of atmospheric pressure changes. Richard Freres of Paris were so confident in their weighted barograph that it was used as a local seismograph when contractors were building the Paris Metro’. 
Interestingly, the Canadian Meteorological Service developed a sprung barograph in the 1950s and was used in their version of the British Met Office Open Scale Barograph.