1S2 SIXTH REPORT — 1836. 



Mr. Braham exhibited an improvement on Pope's fluid compass, by 

 which he hoped to prevent wear of the pivot and cap, unsteady action, 

 change of direction in the card, and obhteration of the points stamped 

 on it. 



Dr. Daubeny exhibited an instrument intended for drawing up water 

 from great depths. 



Mr. Hawkins exhibited and described an improvement of Napier's 

 Rods, by J. N. Cossham, Esq. of Bristol. 



The invention consists in cutting each of Napier's rods into ten cubes, 

 and in stringing the cubes together by means of pins passing through 

 two perforations in each cube, the perforations being made at right an- 

 gles to each other, and parallel to the planes and boundaries of the fi- 

 gured faces, and passing by without crossing the middle of the cube. 

 By this arrangement the cubes may be readily placed in such positions 

 that the product may be obtained by addition only, without the necessity 

 of previously transcribing the number from the cubes, thus avoiding a 

 great liabiUty to error, and eifecting a saving of time in the calculation. 



Mr. John Murray forwarded for exhibition a model of a life boat 

 upon a new construction, accompanied by descriptive notices, and a 

 work printed upon paper made from the New Zealand flax, {JPhormium 

 tenax.) 



STATISTICS. 



Researches relative to the Price of Grain, audits Influence oji the French 

 Population. By Baron Dupin, President of the Institute of France. 



In this communication the Baron obsei-ved that the small annual va- 

 riation in births, deaths, and marriages, even for years of great diff"erence 

 of price, induced him to search for a function of these three social ele- 

 ments, which would both render the variations more perceptible, and 

 correcting one by the other, would remove the perturbations arising 

 from accidental causes. This function is the mean between the numbers 

 of births divided by the number of deaths, and the number of marriages 

 divided by the number of deaths. It is sufficiently obvious that this 

 function is independent of the amount of population, and the Baron 

 considered that the magnitude is a very fair test of social prosperity. 

 He proposed to name it the function of vitality. In the years of extreme 

 scarcity, the function of vitality averaged 0'5937 ; in the years of high 

 prices it averaged 0'6092; in the years of intermediate prices it ave- 

 raged 0"6168. He then observed that according to Dr. Cleland's paper, 

 read on the preceding day, the function of vitality in Glasgow was about 

 0'7000, a clear proof that social happiness was greater in England than 

 in France. He trusted that this function would be calculated for the 

 principal continental nations, and for difl^erent epochs, in order to com- 

 pare their social prosperity by a precise and identical standard. As one 



