And I believe there is none ignorant of this who understands what is written in this Science. Upon this account writing to you, I might call it perfect, albeit I know there are many things relating to the proportion and acceleration of the motions of fluids, which are yet unknown, and may perchance still be. Ye shal not think that I speak of you without ground; (for in your _Ars Magna et Nova_, ye bring in your great attempts for a perpetual motion; all which a novice of eight days standing in Hydrostaticks would laugh at). I do not question that this age hath many advantages beyond former ages; but I know not any of them, it is beholden to you for: only I admire your simplicity in this. Astronomers seek always to have the greatest intervals betwixt Observations, and ye talk that ye will give an excellent way for observing the Sun or Moon’s motion for a second of time; that is to say, as if it were a great matter that there is but a second of time betwixt your Observations. I wonder ye tell me the eye should be added; for the invention had been much greater had that been away. I do confess that a good History of Nature is absolutely the most requisite thing for learning; but it is not like that you are fit for that purpose, who so surely believe the miracles of the West, as to put them in print; and record the simple meridian altitudes of Comets, and that only to halfs of degrees or little more as worth noticing. However, if ye do this last part concerning Coal-sinks well, and all the rest be but an _Ars Magna et Nova_, ye may come to have the repute of being more fit to be a Collier than a Scholar. Ye might have let alone the precarious principles and imaginary worldes of Des Cartes, until your new inventions had made them so: For I must tell you Des Cartes valued the History of Nature, as much as any experimental Philosopher ever did, and perfected it more with judicious experiments, than ye will by all appearance do in ten ages. Ye are exceedingly misinformed, if ye have heard that any here have prejudice or envy against you; for there is none here speaks of you but with pity and commiseration: neither heard I ever of any man who commended you for what he understood. As for your Latin Sentences, if they be not applied to yourself, I understand them not; for here we are printing no books, we are not sending tickets throughout the country to tell the wonders we can do: We are going about the imployments we are called to, and strive to give a reason for what we say. Where then are our _Doli et fallaciae, tabulae et testes, sapientia ad quam putamus nos pervenisse_? etc. In these things ye publish, ye know there is no Sophistry but clear evidence: If ye had done such great matters in _Universale et ens rationis_, ye might have had a shift; but here ye must either particularize your inventions, or otherwise demonstrat yourself derogatory to the credit of the Nation: For what else is it to confound R. Societies and Universities with _Ars