an unpublished letter from henry oldenburg to johann heinrich rahn

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260 Noel Malcolm
fuit. Quae tuae nunc occupationes, planè me latet, non tamen nisi graves et splendidae esse possunt,
ubicunq[ue] terrarum degas, modò genio atq[ue] merito tuo congruant.
Antequam negotia publica me obruerent, exercitationes opticae ferè totum me occupârunt,
quo verò successu illi judicent, qui tubos à me fabrefactos vident, Exemplar tubi [retinui], 69 qui
à sex usq[ue] ad viginti quinq[ue] pedes usui est: nam ope variorum ductuum facile producitur,
retrahiturq[ue]. Quatuor lentibus convexo-convexis constat, unâ quidem objectivâ, et 3 ocularibus
quae parvo tubulo immissae, seorsum majori inserantur; sed quo artificio singula adaptentur,
non attinet hic referre, quoniam universa recensere, nimis longum foret.
Amicus quidam mihi persuadere voluit, quasi Secretarius Societatis Regiae Britannicae,
ante biennium et quod excurrit, literas ad me dedisset, quas apud Mercatores nostros atq[ue]
Basileenses frustrà quaesivi, ne itaq[ue] suspicio sit, quasi ex proposito responsum intermiserim,
etiam atq[ue] etiam rogo, ut talem inurbanitatis notam, à me semovere non 70 designeris.
Hisce vale, Vir celeberrime, meiq[ue] memor esse perge.
Famigeratissimi nominis tui devotissimus cultor
Henr. Rhonius Tig: Senator Quaestor et rerum criminaliu[m] praeses
Tiguri d. 17 Aprilis 1675.
[annotated by Pell:] Doctor Pel received this letter, May XI. 1675 71
Translation
I have received the Algebra—no longer ‘my’ Algebra, but rather, on many accounts, yours—
which, thanks to your generosity, was sent to me by a certain scholar; from it, I gather that my
memory is still flourishing with you, after the passing of so many years. When you were worthily
fulfilling the role of [English] Resident, you conferred so many favours on me, so often, that
whenever they come to mind, it causes me no slight pain to think that I have no ways of repaying
them that would suitable to my obligations—all the more so, since they are so augmented by
this favour of a new kind, that I shall never be capable of deserving them.
I am so unskilled in the English language that I would indeed be completely ignorant of
the contents of that book, were it not for the fact that my name occurs in the preface, and that the
pages that follow expound the method which you invented. I have immediately observed many
things which cast great light on the subject; so I shall shortly procure a translation. I thank you
as much as I can for such a pleasing and welcome gift. That book encourages me—if God gives
me leisure—to go back to the study of algebra, a field of study in which I always took extreme
delight. I am completely in the dark about what your present occupation is, but I am sure that,
wherever in the world you are living, it must be important and distinguished—so long as it suits
your talent and your merit.
Before I was overwhelmed by public business, I was almost completely absorbed in optical
researches; how successful I was therein, those people may judge who saw the telescopes I
made. I have kept an example of a telescope which can be used at a length of from six to twentyfive
feet: for by means of various parts that can be drawn out, it can easily be extended or
retracted. It comprises four convexo-convex lenses: one, indeed, is the objective, and three are
eye-pieces which, placed inside the small tube, can be inserted separately into the larger one. But
it would be out of place to describe here the way in which the individual parts may be fitted
together, as it would take much too long to explain everything.
A certain friend has given me to understand that the Secretary of the British Royal Society
sent me a letter more than two years ago; I enquired for it in vain among the merchants of both
Zurich and Basel. So let it not be suspected that I deliberately delayed replying; I urgently beg
you not to attribute such a sign of impoliteness to me.
With this I say farewell, most famous man, and ask you to continue to remember me—the
most devoted cultivator of your reputation, about which so much is said,
Heinrich Rahn, Senator of Zurich, Judge and President of the Criminal Court
Zurich, 17 April 1675