42 



were tried on a larger scale than the former, and were applied more 

 especially to the practical purposesof building. He recommends that 

 the cement should not be applied in two coats, the surfaces being 

 less likely to adhere when this is done, than if the whole cement is 

 applied at once. He succeeded in various ways, in forming cements 

 which appeared to be the same, in all their properties, with natural 

 cements : and he has now employed them in buildings on a scale 

 sufficiently extensive, and in situations sufficiently exposed to the 

 weather, to be brought to the test of experience in the course of 

 time. Some experiments were also made by the author, with the 

 view of forming an artificial lithographic stone, by a calcined mix- 

 ture of chalk and carbonate of magnesia : but their density could 

 not be rendered such as to answer the purpose intended. 



On the whole he draws the general conclusion, that in all attempts 

 to imitate the water cements of nature by artificial means, carbonate 

 of lime must be the essential ingredient ; next to which in point of 

 importance are silica and alumina. The author succeeded in form- 

 ing a very good cement by uniting these three ingredients. By the 

 addition of a small proportion either of the protoxide of iron or of 

 the oxides of lead, or of manganese, the qualities of the compound 

 were very much improved ; these latter ingredients appearing to 

 produce a more intimate union of all of them, and a more speedy 

 and permanent induration of the mass. 



A paper was read, " On the Meteorological Observations made 

 at the Apartments of the Royal Society, during the Years 1827, 

 1828, and 1829." By J. W. Lubbock, Esq. V.P. and Treasurer of 

 the Royal Society. 



The author first inquires into the annual and diurnal variations 

 of the barometer and thermometer, for the determination of which 

 he takes the mean of the observations in each month made at the 

 Apartments of the Royal Society, during the years 1827, 1828, and 

 1829; and also that deduced from Mr. Bouvard's observations, pub- 

 lished in the Memoirs of the French Academy of Sciences. From 

 the table given it would appear that the annual variations are inde- 

 pendent of the diurnal variations. A much greater number of ob- 

 servations than we possess at present, made frequently and at stated 

 times each day, are requisite before any very satisfactory conclusion 

 can be deduced as to the influence of the moon on the fluctuations 

 of the barometer. The author, however, has attempted the inquiry, 

 as far as the limited range of the present records will allow, by clas- 

 sifying all the observed heights, corresponding to a particular age 

 of the moon, as defined by her transit taking place within a given 

 half hour of the day ; and thence deducing mean results, which are 

 exhibited in tables. 



The results afforded by the observations at Somerset House 

 differ widely from those obtained from corresponding observations 

 made at the Paris Observatory. According to the former, the ba- 

 rometer is highest at new and full moons, and lowest at the qur- 

 dratures the extent of the fluctuations being 0.08 of an inch : ac- 



