TO CORRESPONDENTS. 



Communications have been received from Mr. Tredgold, Leander, Mr. I. New- 

 ton, Mr. T. S. Davies, and Mr. .1. Moore; some of which from the press of matter 

 for the present Number we have been obliged to defer ; but they will all meet with 

 the earliest attention. 



In reply to Mr. By water, we have to state that his "Microscopic Observations" 

 appeared to be too speculative, and not sufficiently definite, for insertion in a pub- 

 lication professing to 3"ecord the progress of inductive science : we intend how- 

 ever to notice his work in a future number. 



We shall not henceforward attend to any communications of which the post- 

 age is not paid. 



PHARMACOPCEIA LONDINENSIS, 



Iterum recognita et retractata, IBS*, p. 6. 

 " A CID UM A CETIC UM FOR TI US," 

 'vel 

 " Acidum Aceticum e Ligno destillatum," 



PURE CONCENTRATED ACETIC ACID, agreeable to the Sample 

 furnished at the request of the Committee of the Royal College of 

 Physicians, may be had of the Manufacturers, BEAUFOY & CO. South 

 Lambeth, London. 



ENGRAVINGS. 



Vol.LIV. A Plate illustrative of the Menai Bridge. — A Plate illus- 

 trative of Mr. Lowe's Description of a Mercurial Pendulum. — A Plate 

 illustrative of Mr. Hare's Calorimotor, a nev? Galvanic Instrument. — A 

 Plate illustrative of Captain Sabine's Paper on Irregularities observed in 

 the Direction of the Compass Needles of the Isabella and Alexander in 

 the late Voyage of Discovery; and Mr. Scoresby's Anomaly in the Va- 

 riation of the Magnetic Needle as observed on Ship-board. 



Vol. LV. A Plate exhibiting a Sketch of the Comet's Path of July 1819. 

 — A Plate illustrative of the Annular Eclipse of the Sun on the 7th of 

 September next. — A Plate illustrative of Mr. Lane's Instrument for 

 gathering Fruit ; • Mr. Young's Mode of preparing Opium from the 

 Papaver somniferum; and of Captain Forman's Essay on a Property in 

 Light. — A Plate descriptive of Mr. Cuthbert's Hydro-pneumatlc Ap- 

 paratus, &c.-:-A Plate illustrative of Capt. Forman's Essay on the Reflec- 

 tion, &c. of Light ; and Mr. Charles Bonnycastle's Communicacion 

 rcspectine tlie Influence of Masses of Iron on the Mariner's Compass. 



Vol. LVI. A Plate illustrative of Mrs. Ibbetson's Paper On the Phy- 

 biology of Botany. — A Plate illustrative of Mr. Hall's Percussion Gun- 

 Lock; of Dr. Kitchinfr's Pancratic Eye-Tube; and of Mr. Park's 

 Mooring Blocks.-^Soctions of Mr. Malam's Gas-Meter. — A Plate ex- 

 hibiting the Discoveries made by Capt. Parry in the Polar Sea. 



Vol. LVII. A Plate illustrative of Messrs. CErsted and Ampere's 

 Electro-magnetic Experiments, and Mr. Perkins's Paper on the Com- 

 pressibility of Water. — A Plate illustrative of Mr. Jamieson's Marine 

 Thermometer Case, and Mr. Jenning's Mercurial Log-Glass.— A Plate 

 illustrative of Dr. Hare's new Modification of Galvanic Apparatus. — A 

 Plate representing a Double Canal Lock, by Mr. R. H. Gower; and a 

 Modifioation of Electro-magnetic Apparatus, by Mr. Tatum. 



