270 Mr. Riddle's Description o/"Barclay's HydrostaticQuadrant, 



A Table of the Strength of Cohesion of Wood, from Experiments 

 by B. Beyan, Civil Engineer. 



Species of Wood 



1. Acacia . . . 



2. Ash .... 



3. Ditto .... 



4. Beech . . . 



5. Birch. . . . 



6. Box .... 



7. Cane .... 



8. Cedar . . . 



9. Chestnut ) 



(horse) J 



10. Ditto (sweet) 



11. Damson . . 



12. Deal, Nor- 1 



way spruce J 



13. Ditto ditto 



14. Do.Christiana 



15. Ditto ditto 



16. Ditto ditto 



17. Do. English 



18. Elder . . . 



19. Hawthorn . 



20. Ditto .... 



21. Holly. . . . 



22. Laburnum . 



23. Lancc-wood 



24. Lignum Vitae 



25. Lime-tree . 



26. Mahogany . 



Spec 

 Grav- 



•85 

 •84 



•78 



•72 



•64 

 •99 

 •40 

 •54 



•61 



•61 



•79 



•34 



•46 

 •46 

 •46 

 •47 

 •73 

 •91 



•76 



•92 



1-01 



1*22 



76 



87 



Cohesion 

 in lbs 



16,000+ 

 16,700 

 19,600 

 22,200 

 15,000- 

 15,500- 

 6,300 

 11,400 



12,100- 



10,500- 

 14,000 



18,100+ 



17,600+ 

 12,400 

 12,300 

 14,000 



7,000 

 15,000 

 10,700- 



9,200 

 16,000 

 10,500 

 23,400+ 

 11,800 

 23,500 + 

 21,800 + 



Species of Wood. 



Mahogany . 

 Maple . . . 

 Mulberry . 

 Oak, English 

 Ditto . . . 

 Ditto, old . 

 Oak pile out J 



of the river \ 



Cam. . . . J 

 Oak, black ) 



Line, log ) 

 Oak, Ham- ) 



boro' ) 

 Ditto ditto 

 Pine, Pe- } 



tersburg { 

 Do. Norway 

 Ditto ditto 

 Do. Peters- ) 



burg . t 

 Poplar . . 

 Sallow . . 

 Sycamore 

 Teak, old 

 Walnut . 

 Willow . 

 Yew . . . 



Spec. 

 Grav 



•80 

 •66 

 •66 

 •70 

 •76 

 •76 



•61 



•67 



•66 

 •66 



•49 



•59 



■66 



•55 



•36 

 •70 

 •69 

 •53 

 •59 

 •39 

 •79 



Cohesion 

 in lbs. 



16,500 



17,400 



10,600 



19,800+ 



15,000 



14,000 



4,500 



7,700- 



16,300+ 



14,000 



13,300- 



12,400 

 14,300 



13,100+ 



7,200- 

 18,600+ 

 13,000 



8,200 



7,800 

 14,000 



8,000 



XLI. A Description of Barclay's Hydrostatic Quadrant, and 

 an Account of Observations made 'with it. By Edward 

 Riddle, Esq. 



To the Editor of the Philosophical Magazine and Journal. 



Sir, 

 \ MONG the various improvements that have been made 

 -^*- in nautical science and nautical instruments within the 

 last fifty years, it has often been regretted that no instrument 

 has hitherto been invented by which altitudes may be taken 

 at sea, to any useful degree of exactness, independent of the 

 horizon. The inventor of such an instrument would confer 

 a most important benefit on all who are connected with mari- 

 time affairs, as it frequently happens even when the celestial 



luminaries 



