NEW APRIL 2019.  Nearly everyone has heard of the Walschaert valve gear, but hardly anyone knows how it works. It takes a brave writer to set out to explain it, but the author of this booklet is certainly one of them. There are eight pages of text, and four pages of drawings marked with numbers which relate to his account. He writes with authority and with commendable clarity (though, unavoidably, an ability in the reader to picture things in more than one dimension is a great help!). He starts with a brief biography of Egide Walschaert, then devotes most of the work to building up a description and an explanation of the gear one step at a time.

The work bears no mention of who wrote it, nor who it was written for. Its format is typescript on ageing sheets of quarto paper, held together with rusty staples. That, and what it says ("The Walschaert valve gear is being fitted to ever-increasing numbers of new engines..." and "...engineers are agreed that this gear fulfils most of the requirements of the modern high-speed superheated engine"), suggest that it probably dates back to the earlier decades of the twentieth century - the 1920s, perhaps.

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