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""A very rare ether vaporizer designed by John Snow,""

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(May 2009)History of Anaesthesia Society, Proceedings, 41 (2009): 105-22. Paper based on a presentation at the 2009 Summer Scientific Meeting, held at the Hilton Bath City Motel, Bath (UK), 29-30 May 2009

Posted with permission of the authors and the Council of the History of Anaesthesia Association.

This article is excerpted from the Proceedings available to anyone for free at .


Page 105 of PDF: Snow described the Mark II vaporizer on 19 March 1847, not 12 March 1847.

Page 120 of PDF: Snow first used his own, modified version of Sibson's face mask in an operation at St. George's Hospital on 10 June 1847, not 17 June 1847. Click on the preceding bolded date to see an engraving of this face mask which Snow used from this point forward.

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[From the summary:]

"An ether vaporizer designed by John Snow and owned by the Royal College of Physicians of London has been identified as the "Mark II" model which he described on 12 March 1847. The facemask is a prototype of the design which he published in September 1847, and can be dated to between mid-May and mid-June 1847. The case contains a unique and previously undescribed thermo-etherometer. This is a thermometer which incorporates Snow's table showing the amount of ether taken up by 100 cubic inches of air at different temperatures."

The authors have provided supplemental photographs which are posted below, with references to parallel figure numbers in the article.


A different view of Fig. 2, showing the contents of the carrying case, as well as the case itself.


A different view of Fig. 4, depicting external sides of the carrying case.



Two additional views of the facemask, which appears in Fig. 7.


Photograph of the thermo-etherometer in its entirety, which is divided in Fig. 5.

With assistance from George Bause, the authors were able to compare the RSM model with a similar vaporizer owned by the Wood Library-Museum:


This apparatus may be viewed in a 3-D video on the WL-M web site ( > Museum > Masks & Inhalers > Snow Inhaler, Mark II).

The mouth piece attached to the WL-M vaporizer is a modification of the mouth piece depicted in an engraving on page 501 of Snow's 19 March 1847 article in which he first described this model.

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