VOL. I.] PHILOSOPHICAL TRANSACTIONS. 13 



An Account of Micrographia, or the Physiological Descriptions of 

 Minute Bodies, made by magnifying Glasses. By Mr. Robert 

 Hook. N" 2, p. 27- 



Hook's Micrographia, or Physiological Descriptions of Minute Bodies, still 

 maintains a deserved reputation ; many of the figures are a kind of standard repre- 

 sentations, from which most succeeding authors on similar subjects have copied. 

 Among the most excellent, though not altogether free from minute faults, are 

 those of the common mite, the flea, the louse, the gnat, and the ant. The 

 figures were all drawn by his own hand. A new edition of this work, with 

 abbreviated descriptions, was published in the year 1745. In this edition the 

 part relative to the Baroscope the Hygroscope, the engine for grinding optic 

 glasses, &c. is omitted. 



Some Observations and Experiments upon May-Dew.* By Mr. Thomas 



Henshajf. N" 3, p. 33. 



That ingenious gentleman, Mr. Thomas Henshaw, having had occasion to 

 make use of a great quantity of May-dew, did, by several casual essays on that 

 Subject, make the following observations and trials, and present them to the 

 Royal Society. 



It appears from this paper that dew, far from being a pure or unadulterated 

 water, is in reality of a more mixed nature than most others. 



Dew newly gathered and filtered through a clean linen cloth, though it be 

 not very clear, is of a yellowish colour, somewhat approaching to that of 

 urine. In moderate quantities, it does not easily putrify, though kept for a 

 long time ; but in large quantities, as of four or five gallons, it putrifies, and 

 deposits a black sediment. 



Mr. Henshaw having several tubs with a good quantity of dew in them set 

 to putrify, and being about to pour out of one of them to make use of it, 

 found in the water a great bunch, larger than his fist, of those insects com- 

 monly called hog-lice or millepedes,-^ tangled together by their long tails, one 



* What is commonly called May-dew is a sweet but excrementitious liquor discharged from the 

 bodies of small insects infesting the leaves of plants, and known to naturalists by the name of 

 Aphides. They are called by the French pucerons. 



t The insects here improperly called millepedes appear rather to have been the larvae or mag- 

 gots either of the musca pendula or tenax. The otlier insects which Mr. H. observed, were the lan-ae 

 or maggots of the common gnat, &c. The most important part of the paper is the concluding para- 

 graph, demonstrating that a great quantity of saline matter is contained in the dew. The precise na- 

 ture of this saline matter remains yet to be ascertained, and is unquestionably a subject which well 

 deserves to be investigated by modern chemists. 



