The manner in which facts apparently lost are restored to light, even after considerable intervals of time, is sometimes very unexpected, and a few examples may not be without their use. The thermometers employed by the philosophers who composed the Academia Del Cimento, have been lost; and as they did not use the two fixed points of freezing and boiling water, the results of a great mass of observations have remained useless from our ignorance of the value of a degree on their instrument. M. Libri, of Florence, proposed to regain this knowledge by comparing their registers of the temperature of the human body and of that of some warm springs in Tuscany, which have preserved their heat uniform during a century, as well as of other things similarly circumstanced. Another illustration was pointed out to me by M. Gazzeri, the Professor of Chemistry at Florence. A few years ago an important suit in one of the legal courts of Tuscany depended on ascertaining whether a certain word had been erased by some chemical process from a deed then before the court. The party who insisted that an erasure had been made, availed themselves of the knowledge of M. Gazzeri, who, concluding that those who committed the fraud would be satisfied by the disappearance of the colouring matter of the ink, suspected (either from some colourless matter remaining in the letters, or perhaps from the agency of the solvent having weakened the fabric of the paper itself beneath the supposed letters) that the effect of the slow application of heat would be to render some difference of texture or of applied substance evident, by some variety in the shade of colour which heat in such circumstances might be expected to produce. Permission having been given to try the experiment, on the application of heat the important word reappeared, to the great satisfaction of the court. CHAPTER VI. SUGGESTIONS FOR THE ADVANCEMENT OF SCIENCE IN ENGLAND. SECTION 1. OF THE NECESSITY THAT MEMBERS OF THE ROYAL SOCIETY SHOULD EXPRESS THEIR OPINIONS. One of the causes which has contributed to the success of the PARTY, is to be found in the great reluctance with which many of those whose names added lustre to the Society expressed their opinions, and the little firmness with which they maintained their objections. How many times have those whose activity was additionally stimulated by their interest, proposed measures which a few words might have checked; whilst the names of those whose culpable silence thus permitted the project to be matured, were immediately afterwards cited by their grateful coadjutors, as having sanctioned that which in their hearts they knew to be a job.