Downloads

Select a blue file name to open a described document or a grey or teal address to open a link.

COMPUTER AIDED DESIGN of the HARRISON SINGLE PIVOT GRASSHOPPER ESCAPEMENT GEOMETRY. CAD SINGLE PIVOT  A versatile Computer Aided Design (CAD) technique enabling the creation of single pivot grasshopper escapement geometries. Includes relevant, detailed explanations of component behaviour, a safe start-up procedure and a complete escapement cycle.

ANIMATION of a HARRISON COMPLIANT SINGLE PIVOT GRASSHOPPER ESCAPEMENT. https://www.youtube.com/watch?v=7TBWJC0HYRE&list=UU2h07cGBpJs8bF3OkgtJICg  A beautiful animation of a single pivot grasshopper escapement by ‘Ken Kuo’ is currently (at 11th August 2014) available on YouTube. Simply left click the above link, or instead locate the video by its creator: ‘Ken Kuo’ and title: ‘One Pivot Grasshopper Escapement – John Harrison’ (but note that the link opens a playlist of many more wonderful Ken Kuo animations, although none of the alternative single pivot grasshopper escapements comply with John Harrison’s stipulations). The escapement geometry and mechanical arrangement are derived from the CAD article listed in the paragraph directly above this. Observe how pendulum overswing and the consequent escape wheel recoil have been deliberately emphasised, in order to clearly demonstrate how and when each composer is lifted from its resting position and how and when one pallet nib locking corner is captured and the other pallet nib locking corner is simultaneously released. It is worthy of note that the single pivot Harrison grasshopper escapement shown in the video at https://www.youtube.com/watch?v=P08tHF6rKgc operates in accordance with precisely the same principles as above, but with far less obvious recoil. In particular, there is almost undetectable (although, be assured, still present) exit composer lift.

COMPUTER AIDED DESIGN of HARRISON TWIN PIVOT and TWIN BALANCE GRASSHOPPER ESCAPEMENT GEOMETRIES. CAD TWIN PIVOT and BALANCE  Versatile Computer Aided Design (CAD) techniques enabling the creation of twin pivot (‘Brocklesby’ style) and twin balance (‘sea clock’) grasshopper escapement geometries. Relevant, detailed explanations of twin pivot component behaviour, a safe start-up procedure and a complete escapement cycle are included.

ANIMATION of a HARRISON COMPLIANT TWIN PIVOT GRASSHOPPER ESCAPEMENT. https://www.youtube.com/watch?v=swGGflJd71I&list=UU2h07cGBpJs8bF3OkgtJICg&index=1 A beautiful animation of a twin pivot grasshopper escapement by ‘Ken Kuo’ is currently (at 11th August 2014) available on YouTube. Simply left click the above link, or instead locate the video by its creator: ‘Ken Kuo’ and title: ‘Two Pivot Grasshopper Escapement – John Harrison’ (but note that the link opens a playlist of many more wonderful Ken Kuo animations, although none of the alternative twin pivot grasshopper escapements comply with John Harrison’s stipulations). The escapement geometry and mechanical arrangement were derived from the CAD article listed in the paragraph directly above this. Observe how pendulum overswing and the consequent escape wheel recoil have been deliberately emphasised, in order to clearly demonstrate how and when each composer is lifted from its resting position and how and when one pallet nib locking corner is captured and the other pallet nib locking corner is simultaneously released.

A “TRANSLATION” OF HARRISON’S 1775 MANUSCRIPT ‘CONCERNING SUCH MECHANISM…’ CSM TRANSLATION  With the firm objective of enabling access to what is widely regarded as a prohibitively complex and time-consuming manuscript, this publication is a modern (2011) “translation” of John Harrison’s final (1775) pamphlet, commonly referred to as “Concerning Such Mechanism” or “CSM”.

♦♦♦ HARRISON’S ESCAPEMENT IMPULSE IS AS EASY AS 1, 2, 3. HARRISON’S IMPULSE IS AS EASY AS 1, 2, 3  John Harrison’s 1775 manuscript ‘Concerning Such Mechanism…’ (CSM) includes poorly expressed stipulations for the delivery of single pivot grasshopper escapement impulse : ‘…let, as I order the Matter, the Force [from the Wheel] upon the Pendulum, as just before the interchanging of the Pallats, to be as by or from them the said Pallats supposed or taken as 3, then as just after their interchanging [and the Force to contrary Direction], it must be about as 2, that is, it must be so ordered [as may hereafter be observed by the Drawing] viz as that it be so by the taking, or supposing for the Purpose, a Mean betwixt the Actions of each Pallat…’ Sadly, Harrison later declares that ‘…the Drawing…’ and a more detailed explanation will no longer be offered, in response to poor treatment and incomplete reward by the Board of Longitude. It is considered fair to conclude that Harrison’s deliberate exercise in self-sabotage has thus far committed his remarkable invention to two hundred and thirty seven years of effectively universal misrepresentation. Fortunately, all is not lost. This analysis will support a proposal that the unpublished drawing was, in fact, created after all and that it still exists. Of greatest value to a correct understanding of Harrison’s escapement principles, it will be demonstrated that the illustration incorporates a complete and unambiguous definition of his precise intentions for the delivery of impulse.

HOW MANY TEETH SHOULD A HEALTHY GRASSHOPPER HAVE? HOW MANY TEETH SHOULD A HEALTHY GRASSHOPPER HAVE Orthopteran Orthodontistry? Please note carefully that, since the publication of this analysis, mathematical modelling has been displaced by far more versatile and capable graphical techniques, most accurately (although not essentially) created using widely available Computer Aided Design (CAD) software (see ‘COMPUTER AIDED DESIGN of the HARRISON SINGLE PIVOT GRASSHOPPER ESCAPEMENT GEOMETRY’ and ‘COMPUTER AIDED DESIGN of HARRISON TWIN PIVOT and TWIN BALANCE GRASSHOPPER ESCAPEMENT GEOMETRIES’, above). Note in particular that mean torque ratio is replaced by mean end/start ratio.

HOW BIG A KICK SHOULD A HEALTHY GRASSHOPPER HAVE?  HOW BIG A KICK SHOULD A HEALTHY GRASSHOPPER HAVE  Orthopteran Orthopaedics? Please note carefully that, since the publication of this analysis, mathematical modelling has been displaced by far more versatile and capable graphical techniques, most accurately (although not essentially) created using widely available Computer Aided Design (CAD) software (see ‘COMPUTER AIDED DESIGN of the HARRISON SINGLE PIVOT GRASSHOPPER ESCAPEMENT GEOMETRY’ and ‘COMPUTER AIDED DESIGN of HARRISON TWIN PIVOT and TWIN BALANCE GRASSHOPPER ESCAPEMENT GEOMETRIES’, above). Note in particular that mean torque ratio is replaced by mean end/start ratio.

THE UNILATERAL TWIN PIVOT GRASSHOPPER ESCAPEMENT. THE UNILATERAL TWIN PIVOT GRASSHOPPER ESCAPEMENT All currently known written, illustrated and/or physical evidence attributable to John Harrison indicates that he invented and constructed three configurations of the grasshopper escapement: the twin pivot, the single pivot and the twin balance. There is, however, currently no written, illustrated or physical evidence that Harrison ever identified, recorded or constructed a fourth configuration, which will be referred to as the ‘unilateral twin pivot’ or ‘UTP’ grasshopper escapement. A concise description and explanation is presented in this study.

♦♦♦ ANIMATION of a HARRISON COMPLIANT UNILATERAL TWIN PIVOT GRASSHOPPER ESCAPEMENT. https://www.youtube.com/watch?v=fBfp9riiJxc  A beautiful animation of a unilateral twin pivot grasshopper escapement by ‘Ken Kuo’ is currently (at 26th January 2015) available on YouTube. Simply left click the above link, or instead locate the video by its creator: ‘Ken Kuo’ and title: ‘Unilateral Twin Pivot Grasshopper Escapement (UTP Grasshopper Escapement)’ (but note that the link opens a playlist of many more wonderful Ken Kuo animations, although none of the alternative twin pivot grasshopper escapements comply with John Harrison’s stipulations). The escapement geometry and mechanical arrangement were derived from the article listed in the paragraph directly above this. Observe how pendulum overswing and the consequent escape wheel recoil have been deliberately emphasised, albeit only slightly, in order to clearly demonstrate how and when each composer is lifted from its resting position and how and when one pallet nib locking corner is captured and the other pallet nib locking corner is simultaneously released. It should be noted that, as explained in my single and twin pivot/twin balance articles offered earlier, the degree of pallet arm ‘bounce’ when contacting its paired composer may (and, in this example, should) be altered (for example) by increasing or decreasing the relevant pallet arm tail weight and/or the (polar moment of) inertia of the arm. Alternative arm and/or composer materials are another obvious influence, although hardwood arms and brass composers are the proven combination, as used by Harrison. The objective is to avoid continued bouncing of the pallet nibs when they meet the escape wheel, to ensure frictionless operation and secure nib capture. As an aside, whilst mentioning the subject of materials, lignum vitae is currently a popular pallet arm and nib material for some strange reason. Why would a sensible engineer use a hardwood renowned for its low friction, when the objective is to generate reliable nib locking corner capture?

♦♦♦ Link to YouTube videos by this author (under username ‘glathoppa’): http://www.youtube.com/user/glathoppa

Link to images of HARRISON’S ORIGINAL 1775 MANUSCRIPT ‘CONCERNING SUCH MECHANISM…’: http://cudl.lib.cam.ac.uk/view/MS-ZAA-00883/1 This observer disagrees with many of the modern, introductory comments accompanying the images of Harrison’s CSM, as follows: (1) – The certainty that Harrison employed others to manufacture components in accordance with his instructions is entirely irrelevant to his deserved status as a pioneering horological genius. More significant is the complete lack of evidence that Harrison received or requested any research, design, development or creative support from his contemporaries. In those four respects, all currently available information leads to the inarguable conclusion that Harrison worked entirely alone. Put simply, it is nothing short of ridiculous to claim that Harrison fails to qualify as a ‘lone genius’ merely because he employed others to saw, file, machine and polish brass and steel in accordance with his instructions. (2) – The conclusion that Harrison failed to invent a practicable method of determining longitude at sea because his timekeepers were too expensive to manufacture is inaccurate and misleading. Single prototypes are often expensive, sometimes ridiculously so, and Harrison’s prototype H4 was certainly no exception. However, subsequent versions by Harrison and Kendall were, in some cases, considerably less expensive, despite adequate performance. Of greater relevance, Harrison was the first to demonstrate that longitude at sea could be determined with unprecedented accuracy using a timekeeping method. No less a scientist than Sir Isaac Newton was thereby proven to be wrong. To diminish Harrison’s achievement and its considerable influence upon the future development of the marine chronometer is grossly unfair. (3) – To suggest that The Board of Longitude behaved entirely fairly towards Harrison is to ignore current evidence to the contrary. Accounts of the behaviour of The Board of Longitude are on record; why ignore them? (4) – It is claimed that ‘Throughout his interaction with the Board of Longitude, Harrison was accused of not making clear enough the principles of his inventions or ‘discoveries”. This comment entirely ignores Harrison’s concerns that, had he revealed his principles in any detail before securing The Longitude Prize, his inventions and discoveries would almost certainly have been plagiarized, thereby jeopardizing his claim to the prize. Furthermore, the unreasonably lengthy delay in awarding Harrison less than the promised Longitude Prize was also responsible for his disinclination, inarguably recorded in CSM, to fully explain his principles of precision timekeeping: ‘…but as being paid short, and that as farther withal, to be attended with a great deal of expence, trouble, and hinderance, (scurvy work) I will also be short…’.

Link to National Association of Watch and Clock Collectors (NAWCC) Chapter #161 – Horological Science: http://www.hsn161.com

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s