The whole sequence starts with the review I posted here of Eileen Reeves' brand new "Galileo's Glassworks: The Telescope and the Mirror" (2008, Harvard University Press). Though overall very fascinating, one aspect of this book confused me: why it should be structured in two so radically different (dare I say almost schizophrenic?) halves. You see, while the first 50% covers the amorphous literary pre-history of the telescope, the second 50% deals with the textual minutiae of who told Galileo what and when, and what Galileo probably believed in 1608-9: so the book swings sharply from a super-broad cultural reading to an ultra-close textual reading. An uncomfortable mixture.
Now, the first half particularly intrigued me, so it made sense for me to move on to Reeves' major source for it: Albert van Helden's (1977) brief (but magisterial) "The Invention of the Telescope". If you want your own copy, there are still a couple under £25 available on BookFinder.com (though be quick, the rest are over £50).
Van Helden (for whom Dutch is his first language) had started out by translating Cornelis de Waard's relatively little-known book "De uitvinding der verrekijkers" (The Hague, 1906), which laid out a lot of new evidence on the genesis of the telescope as we know it in the Netherlands: much of the story revolved around the town of Middelburg (which held one of the largest glassworks in Europe), with nearly all key documents written in Dutch.
But de Waard's conclusions - that the telescope had probably been invented in Italy circa 1590, that Raffael Gualterrotti had built such a device in 1598, and that one of which had surfaced in Holland circa 1604, before being replicated by various spectacle-makers and inventors in 1608, leading to an unseemly patent rush - seemed to van Helden not quite to be supported by the evidence. And so he decided to take a fresh look at the documents: and his 1977 monograph was the result.
Having said that, van Helden's final conclusions are practically the same as de Waard's, though not quite as specific: that Giovanbaptista della Porta's claim to have built a telescope (to which his "Magia naturalis libri XX" (Naples, 1589), Book XVII, Chapter 10, p.269 circumspectly alludes) probably does hold up, as does Gualterrotti's claim (perhaps more weakly), though given that the best magnification possible pre-1600 would (argues van Helden) have been only around 2x, the resulting device would have been unspectacular - a telescopic amuse-bouche, rather than the Galilean feast that was to come. And so van Helden concludes that Italians (specifically della Porta) probably did invent the telescope, though they didn't realise it at the time.
Thirty years on, and I think van Helden's monograph stands as a great piece of writing: clear, lean, thoughtful, honest. Best of all, the majority of it (pp.28-64) consists of transcriptions (and English translations) of the important sections of all the relevant documents; so if you don't like his conclusions, feel free to go right to the primary sources (they're pretty much all there), knock yourself out. Perfect.
It should now be clear what I think happened with "Galileo's Glassworks". The elephant in the room (who was not mentioend, but around whom all the furniture was carefully arranged) was van Helden's monograph: this forms a bridge between Reeves' two distinct sections. And so if you add the two books together, you get what amounts to a single coherent work, going from medieval and early modern notions and claims of vision-at-a-distance and burning mirrors (Reeves), through to the myriad claims and counterclaims of the Dutch "inventors" (van Helden), through to Galileo's reception of the new device (Reeves again). At only 231 pages (with endnotes starting on p.167), Reeves' book originally felt to me to be about 60-70 pages short: how curious to find that van Helden's monograph exactly fits the dimensions of that lacuna.
In her acknowledgments, Reeves says that she "benefited most of all... from the intellectual guidance and constant friendship of Albert van Helden, whose own work... is the basis of and inspiration for my own" (p.220). I'd say that while Reeves' book gives context and consequence to van Helden's monograph, reading the former without the latter doesn't really make sense. In fact, I would strongly recommend to Harvard University Press (who publish "Galileo's Glassworks") that they negotiate with the American Philosophical Society to reprint Reeves' book with van Helden's excellent (but scarce) work as an appendix. Now that would be a book truly worthy of the International Year Of The Telescope.