ROC 



ROC 



est diligence, and formed complete plans 

 for Fort St. David, and Madras, but he 

 did not live to put them into execution. 

 For the great difference of the climate 

 from that of England being beyond his 

 constitution to support, he was attack- 

 ed by a fever in September the same 

 year; and though he recovered out of 

 this, yet about eight months after he 

 fell into a languishing condition, in 

 which he continued till his death, which 

 happened the 29th of July 1751, at on- 

 ly 44 years of age. 



Ky his last will, Mr. Robins left the 



gublishing of his mathematical works to 

 is honoured and intimate friend Martin 

 Folkes, Esq. President of the Royal So- 

 ciety, and to Dr. James Wilson ; but the 

 former of these gentlemen being incapa- 

 citated by a paralytic disorder, some time 

 before his death, they were afterwards 

 published by the latter in 2 vols. 8vo, 

 1761. To this collection, which contains 

 his mathematical and philosophical pieces 

 only, Dr. Wilson has prefixed an account 

 of Mr. Robins, from which this memoir 

 is chiefly extracted. He added also a 

 large appendix, at the end of the second 

 volume, containing a great many curious 

 and critical matters in various interesting 

 parts of the mathematics. 



It is but justice to say, that Mr. Robins 

 was one of the most accurate and elegant 

 mathematical writers that our language 

 can boast of; and that he made more 

 real improvements in artillery, the flight 

 and the resistance of projectiles, than all 

 the preceding writers on that subject. 

 His new principles of gunnery were 

 translated into several other languages, 

 and commented upon by several emi- 

 nent writers. The celebrated Euler 

 translated the work into the German 

 language, accompanied with a large and 

 critical commentary ; and this work of 

 Euler's was again translated into Eng- 

 lish in 1714, by Mr. Hugh Brown, with 

 notes, in one volume quarto. 



ROBINSONIA, in botany, a genus of 

 the Icosandria Monogynia class and or- 

 der. Essential character : calyx five- 

 toothed ; petals five ; berry striated, 

 two-celled ; cells one-seeded ; seeds vil- 

 lose. There is but one species, viz. R. 

 melianthifolia, a native of Guiana. 



ROCHEFORTIA, in botany, so nam- 

 ed in memory of De Rochefort, a genus 

 of the Pentandria Digynia class and or- 

 der. Natural order of Dumosse. Rham- 

 ni, Jussieu. Essential character: calyx 

 five-parted; corolla one petalled, fun- 

 nel-form, inferior, with the aperture 

 open-, fruit two-celled, many-seeded. 



There are two species, viz. R. cunenla, 

 and R. ovata, both natives of Jamaica. 



ROCK, a stony mass, forming a por- 

 tion of the substance of this globe. 

 Rocks are in general disposed in moun- 

 tanic ranges ; but in some few instances 

 are found existing in immensely large 

 separate masses. 



The obvious differences existing in the 

 appearances and composition of different 

 rocks and mountains have long induced 

 mineralogists to consider them as formed 

 at very distant periods from each other, 

 and even to suppose that those of the lat- 

 ter formation frequently derived the ma- 

 terials of which they were composed 

 from the disintegration of the previously 

 existing and much more ancient rocki. 

 Hence arose their division into primeval, 

 or primitive : and secondary, or epizootic; 

 and in consequence of the prevalence ot' 

 the opinion of the primitive rocks supply- 

 ing the materials of those of secondary 

 formation, the latter were further separa- 

 ted into original and derivative. The 

 secondary rocks were also considered as 

 otherwise differing in their origin ; some 

 being supposed to be marigenous, and 

 others alluvial. 



The celebrated Werner considers all 

 rocks, with respect to their origin, to be 

 aquatic or ignigenous. The aquatic are 

 divided, agreeable to the period, and the 

 particular mode of their formation, into, 

 1. Primitive, being chemical precipitates, 

 bearing no traces ot organized beings, 

 and formed in the early chaotic state of 

 the earth. 2. Transition, formed, as the 

 term implies, during the transition of the 

 earth into a habitable state. 3. Floetz 

 rocks, disposed in flat or horizontal stra- 

 ta, after the creation of animals and vege- 

 tables ; the remains of which are often 

 found in the substance of these rocks : 

 as the primitive are of purely chemical, 

 so the two latter are of partly chemical, 

 and partly mechanical formation. 4. Al- 

 luvial, formed by the component parts of 

 previously existing rocks, separated by 

 the influence of air, water, and change of 

 temperature, and deposited in beds. 5. 

 Volcanic rocks, which, according to their 

 originating from true volcanoes, or from 

 pseudo-volcanoes, are considered as vol- 

 canic, or pseudo-volcanic. 



Mountain rocks are simple, as when 

 formed of limestone, clay-slate, serpen- 

 tine, or any other simple fossil ; and com- 

 pound, when formed by the aggregations 

 of simple fossils. The compound rocks 

 are either cemented, formed of various 

 parts brought together and connected by 



M 



