S H 
 
 ST 
 
 A PROCESS FOR PRESERVING THE PEARL- 
 OYSTER FISHERIES AND FOR INCREASING THE 
 VALUE OF THE YIELD OF PEARLS ^ ^ 
 
 From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
 
 Proceedings of the Fourth Ititernational Fishery Congress 
 
 Washington, igo8 
 
 WASHINGTON :::::: GOVERNMENT PRINTING OFFICE 
 
Qass 
 
 -^^ 
 
A PROCESS FOR PRESERVING THE PEARL- 
 OYSTER FISHERIES AND FOR INCREASING THE 
 VALUE OF THE YIELD OF PEARLS .* ^ 
 
 From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 190S 
 Proceedings of the Fourth International Fishery Congress : : Jlashington, igo8 
 
 Si, 
 
 MASHIXGTON 
 
 GOVERNMENT PRINTING OFFIC1-: :::::: 1910 
 
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 .^^.^ 
 
 <b^' Oo 
 
 BUREAU OF FISHERIES DOCUMENT NO. 660 
 
 Issued Februafy, 1910 
 
 MAR 2 iy,o 
 
c 
 
 A PROCESS FOR PRESERVING THE PEARL-OYSTER FISHERIES 
 AND FOR INCREASING THE VALUE OF THE YIELD OF PEARLS 
 
 ji 
 
 By John I. Solomon, B. Sc. 
 I* 
 
 Presented before the Fourth International Fishery Congress, held at V/ash- 
 ington, U. S. A., September 22 to 26, 1908, and awarded the prize of one 
 hundred dollars in gold offered by the New York Academy of Sciences for the 
 contribution, not entered in competition for any other award, which should 
 be judged to have the greatest practical value to the fisheries or fish culture 
 
A PROCESS FOR PRESERVING THE PEARL-OYSTER FISHERIES 
 AND FOR INCREASING THE VALUE OF THE YIELD OF PEARLS. 
 
 By JOHN I. SOLOMON, B. Sc. 
 
 CONDITIONS IN THE PEARL-OYSTER FISHERIES. 
 
 The process of obtaining natural pearls is carried on throughout the world 
 to-day in precisely the same manner that it has been done ever since mankind 
 has prized this product of the sea as a gem. The only qualification that can be 
 made to the above statement is that since the invention of modern diving appa- 
 ratus there has been, in certain parts of the world, a modification in the method 
 of securing the pearl oyster. This so-called improvement, however, has perhaps 
 done more, within a very few years, to deplete former valuable natural beds 
 than had centuries of previous fishings, when the ability of man to strip the beds 
 of all the oysters they contained was prevented by the limitations of naked 
 diving. The divers could then go to but comparatively shallow depths, and 
 could gather the oysters only in a haphazard manner as they groped about for 
 a minute or two at the bottom. Also, because of the inabihty of naked divers 
 to carry on operations in any but calm and warm weather, the season for fishing 
 was comparatively short. As a result of these conditions the beds in even 
 comparatively shallow waters were never entirely stripped of all their oysters, 
 while those lying at depths greater than the physical ability of the divers to 
 reach were untouched. There were thus always sufficient oysters left for 
 breeding purposes, and in spite of the wastes of the method for securing the 
 pearls — the killing of all the oysters to get the contained pearls from about lo 
 per cent of them — the beds continued to give a comparatively uniform yield. 
 
 Since the adoption of diving apparatus the conditions have entirely changed. 
 With the divers enabled to remain under water for a considerable period and in 
 weather which would prohibit naked diving, and to go to greater depths and 
 work in a thorough and system.atic manner, the old natural beds have been 
 completely stripped, and beds heretofore inaccessible have been or are being 
 depleted in the same way. This has already been accomplished in most parts 
 of Australia, the waters off Thursday Island, Costa Rica, the Mergui Archipelago 
 
3o6 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 of Lower Burma, and in practically all the places heretofore fished by white men. 
 The business in the East, excepting the fisheries of Ceylon and the Persian 
 Gulf, where the local fisheries and conditions due to the nature of the oysters 
 and other local influences are peculiar, is now practically in the hands of Jap- 
 anese and Chinese, who alone are satisfied with the small returns from the now 
 meager beds. The Europeans formerly engaged in the business are seeking 
 other occupations. In Burma most of them have gone into tin mining, and at 
 the present time just a single white man is there engaged in the pearl industry. 
 In Australia and the islands of the East Indies there is a constant exploration 
 now for virgin beds and a seeking for better divers and apparatus to go to greater 
 and greater depths. There one hears a constant wail at the limitations of man 
 and his apparatus to combat the great pressures of depths where the oysters 
 are supposed still to be in abundance, and the more imaginative, speculative, 
 or daring are now talking of submarines to go after the oysters. In this connection 
 I would state that a submarine of special construction has recently been built 
 in France for sponge fishing in the Mediterranean off the coast of Algiers. 
 
 As a result of the wastes of past and present methods and the general 
 conditions of the industry as now carried on, both in the pearl fisheries of the 
 seas as outlined above, and in connection with the fresh-water pearl fisheries 
 of the United States and other countries, the statement has been freely made 
 in the past few years by prominent pearl dealers of Europe and America that 
 no large pearls will ever again come to market, except those in the possession of 
 eastern magnates and potentates who may be induced by the extravagant prices 
 offered to part with heirlooms held in their families for generations. In other 
 words, the pearl of size and value is tending to extinction. Although the 
 scientific propagation of oysters and other shellfish has been made a great com- 
 mercial industry in Europe and America, the idea of conserving the pearl- 
 oyster beds and attacking the problem of securing pearls and shells other than 
 by the ruthless destruction of the natural beds seems never to have entered 
 the minds of those engaged in the industry. I have never received any encour- 
 agement from a single one of them with whom I have corresponded or whom I 
 have met ; and although the installation which I have myself started has proved 
 the undoubted soundness and utility of the process, and the fact of its establish- 
 ment has now become more or less known throughout the East, I have yet to 
 learn of the interest of any individual or corporation engaged in the pearling 
 industry. In view of the recent agitation in the United States because of the 
 destruction of the fresh-water mussel pearl fisheries, I hope that in my own 
 country more interest will be disclosed. 
 
 PRINCIPLE OF THE PROCESS. 
 
 An electrical engineer by profession, my first knowledge of the pearling 
 industry was gained through an acquaintance with a family having social and 
 
PROCESS FOR PRESERVING PEARL-OYSTER FISHERIES. 307 
 
 business relations with Colombia, Panama, and Costa Rica, who thereby had a 
 knowledge of and who dealt in pearls fished in the waters of those countries. It 
 was because of this acquaintance and the knowledge thus gained of the conditions 
 that I conceived the idea of utilizing the X ray for preventing the losses and 
 wastes of present pearling methods and for increasing the yield of fine pearls. 
 In this connection, I would state that I am not the first to have thought of 
 utilizing the X ray for these purposes. Although I did not know it until later, 
 Prof. Raphael Dubois, of the University of Lyons, had a few years before sug- 
 gested such a use of the X ray. I had the pleasure, in the month of December, 
 1907, of paying a visit to Professor Dubois. But from a particular question asked 
 by him I found that his investigations had been slight and not very extensive 
 on living oysters. 
 
 The question asked by Professor Dubois was one which I had great difficulty 
 in explaining away to the laymen whom I induced to become financially inter- 
 ested in my enterprise, "Will the X rays kill the oysters?" I had made this 
 test at the very commencement of my experiments, once I had become enabled 
 by skillful exposure to disclose pearls which I had placed inside of large Rockaway 
 oysters in New York. Having previously made arrangements at the New 
 York Aquarium, I placed in tanks there live oysters which I had subjected to 
 continuous exposure of powerful X rays for as long as a period of ten minutes. 
 These oysters lived for months without showing any ill effects whatever. In 
 my process the time of exposure is not one-tenth of this. I made this experiment 
 only in order to satisfy the minds of my subscribers, for, after consultation with 
 specialists having a full knowledge of the physiological and pathological effects 
 of X rays on animal tissues and organisms, I was myself convinced that the 
 slight exposure necessary for the process could have no effect. 
 
 My first intention and experiments were with the idea of using the fluoro- 
 scope for the detection of the pearls within the living oysters, but having 
 learned that in Ceylon they had taken as many as 41,000,000 oysters at a single 
 fishery (one season) I saw that the conditions were not as in Costa Rica and som.e 
 other places. I accordingly adopted a radiographic method. A comparatively 
 few oysters may be examined individually and carefully by means of the fluoro- 
 scope, but by the other method great numbers may be automatically handled 
 and many inspectors may leisurely examine radiographs made practically 
 automatically ; and the radiographic method in practice has done all I expected 
 if to do. In the same time that would be required to examine a single oyster by 
 the fluoroscopic .method a single tube and operator can make radiographic 
 images of hundreds of oysters, and, as has been found in surgical work, a radio- 
 graph will show up more minute particles and detail than can ever be disclosed 
 by a fluoroscopic examination. 
 
 In order to accomplish the object sought, I had to devise a process and appa- 
 ratus, and I subjoin hereto a description and the claims of the first of several 
 
3o8 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 patents which have been granted to me by the governments of Austraha, Ceylon, 
 India, Japan, and other pearl-producing countries, or countries which have 
 pearl-producing colonies and dependencies. 
 
 DESCRIPTION OF INVENTION AND CLAIMS AS PATENTED. 
 
 The object of this invention is (i) to provide means for taking radiographs 
 or of making fluoroscopic examinations of separate pieces of matter or objects in 
 considerable quantities, so that they may be taken simultaneously for the pur- 
 pose of making radiographic examination of these objects and pieces of matter, 
 and then (2) readily to identify each radiograph as being that of the particular 
 object or piece of which it is the representation. 
 
 The manner of taking radiographs at present is to make exposures of indi- 
 vidual objects placed upon photographic plates, or other sensitive radiographic 
 media, either in direct contact or with the plate properly inclosed in paper to 
 keep out light. The exposures having been made, by means of the X rays, 
 Rontgen rays, or any other rays penetrating matter opaque to light, the object 
 is removed from the plate or other sensitive medium and set aside, the sensitive 
 medium being then developed through ordinary photographic process and 
 examined. 
 
 This method is cumbersome and expensive, and precludes the radiographic 
 examination of many diff'erent materials. Also it can not be utilized in connec- 
 tion with large bodies or numbers of objects for commercial purposes. My 
 particular aim in connection with the present invention is the ascertaining of 
 the presence of pearls of any size or form in pearl oysters {Margaritifera vulgaris) 
 without injury to the oysters; but the invention is not limited with respect to 
 the character of the objects under examination, as it may be used for any objects 
 whatever. Ordinary processes and apparatus could not be used for this pur- 
 pose, for the reason that they would be too cumbersome, slow and expensive, 
 and entirely unsuited. 
 
 For the purpose of examining' the material quickly and cheaply, I utiHze a 
 tray or conveyer of considerable surface, over which the material may be spread 
 or carried, and this tray or conveyer is then laid upon the sensitized radiographic 
 medium. The latter is of a size larger in area than the tray or carrier itself, the 
 excess being sufficient to allow for the distortion due to the rays falling upon the 
 outer area at a considerable angle. 
 
 The exposure having been made, the tray is lifted from the sensitized 
 medium, or in the event of the conveyer it is so adjusted as to be carried beyond 
 the sensitized medium. The latter is then developed, and the resultant radio- 
 graph, which is the full size of the tray, except for the increase in size d«e to the 
 distortion, can be compared to the objects or material on the tray itself, these 
 objects or material not having been disturbed, and occupying at this time the 
 same relative position as in the particular radiograph on the sensitized medium. 
 
PROCESS FOR PRESERVING PEARL-OYSTER FISHERIES. 
 
 309 
 
 When pearl oysters are the objects examined, the pearls will clearly appear in 
 the radiograph, as they obstruct the passage of the rays to a greater extent than 
 other portions of the oysters. I also use in connection with the tray or conveyer 
 a means for identifying the particular group of objects which have been radio- 
 graphed so that the radiograph may be afterwards compared with the objects 
 on the tray and their 
 identity established. With //^ 
 
 pearl oysters, those that 
 have pearls may thus be 
 identified, and the position 
 and size of the pearls be 
 ascertained, without de- 
 stroying the oysters. 
 
 The essentials of the 
 tray bottom or conveyer 
 are two: (i) That the ma- 
 terial be composed of a 
 substance which renders lit- 
 tle or no resistance to the 
 passage of the X rays, 
 Rontgen rays, or any other 
 rays penetrating matter 
 
 opaque to licht and allows ^'°' '' — ^'^° °^ ^^^ '° contain pearl oysters for radiographing. 
 
 them to affect the sensitized medium practically as though it had not been 
 interposed; and (2) that the tray bottom be as thin as possible, in order that the 
 matter when held on it be but little further away from the sensitized medium 
 when on the tray than when placed directly on the sensitized medium, so that 
 as good definition as possible may be obtained. 
 
 The tray may be of any shape or size desired, and may be constructed of 
 
 cork, fiber, wood, fabric, 
 ^ ^ aluminum, celluloid, vul- 
 
 canized rubber, or any 
 other material the qualities 
 of which, as outlined above, 
 are such as to afford the 
 least amount of resistance 
 to the rays. That wet ob- 
 jects may be examined without warping or distortion of the tray, I propose 
 that a tray be made with the bottom of canvas, duck, or other such fabric. 
 Such a receptacle is shown in the attached drawings, of which figure i is a 
 plan and figure 2 a longitudinal section. It consists of a rigid frame (a) made 
 of strips of metal, wood, or other suitable material, and having hooks or pins (b) 
 
3IO 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 on the outside. The canvas (c) can then be placed under this frame, and hav- 
 ing suitable eyelets (d) in its edge, can be stretched tightly upon the frame by 
 a lacing (e) which is passed through the eyelets (d) in the canvas (c) and the 
 hooks or pins (b) on the frame. In order that the radiographs of objects along 
 the sides may be complete and properly made, and be not intercepted by this 
 frame (a), another frame (/), of wood or other material which will allow the 
 rays to pass through, is placed between the canvas and the first frame (a) and 
 secured to the latter by means of screws (g). The frame / projects suffi- 
 ciently inside of the frame a to hold the materials that are being examined at 
 such a distance that the rays {h) pass through the very outside of the material, 
 clear of the frame a, and will produce the desired effect upon the sensitized 
 medium (i) underneath the tray. 
 
 Upon the tray and preferably upon the second frame (/) , or upon the canvas, 
 is placed a number, letter, or some other device by which to distinguish the trays 
 from each other. This sign (k) is here shown as a number (23) , cut out of metal, 
 
 which is impervious to the ray, and properly secured to the frame / or the 
 canvas. 
 
 The invention may be modified, as, for instance, by substitution of a con- 
 veyer in place of the tray. One form of conveyer is shown in figure 3. Here 
 the canvas (c) is an endless strip passing over rollers (//). The frame (a) is 
 shown as raised above the canvas a sufficient height to allow the objects placed 
 upon the canvas td be moved under it. The canvas is in divisions equal in 
 size to the frame, and each division is provided with a distinguishing mark {k), 
 as already described. In operation of this modification, the objects are placed 
 within the frame and upon one division of the conveyer. The sensitized 
 medium (i) is placed under it as shown, and the radiograph is then taken. The 
 conveyer is then moved by turning one or both of the rollers, so that the objects 
 will have passed to one side and an uncovered portion of the conveyer is exposed. 
 More objects are placed upon this within the frame, and a second radiograph is 
 taken. This will be repeated, the first radiographs being developed while others 
 
PROCESS FOR PRESERVING PEARL-OYSTER FISHERIES. 31I 
 
 are being taken. The conveyer belt should be sufficiently long to allow the 
 developed radiograph to be secured and examined with the corresponding orig- 
 inal objects without disturbing the continuity of action of the machine. Each 
 radiograph will have printed upon it the distinguishing character of that portion 
 of the conveyer, and the different objects may be identified before they are 
 disturbed. . 
 
 A further modification of the invention may be made by utilizing the 
 principles of the fluoroscope. In this form, in place of the sensitized medium 
 would be used the ordinary fluoroscope screen, formed of any suitable mate- 
 rial, as, for instance, the tungstate of barium or of strenium, in crystallized 
 form, or barium platinum cyanide. The conveyer carrying the objects should 
 in this case be placed between the X-ra)' tube and the fluorescent screen. 
 
 Having now particularly described and explained the nature of my inven- 
 tion, and in what manner the same is to be operated, I make the following 
 claims therefor: 
 
 (i) The herein described process of examining separated matter or different 
 objects, such as pearl oysters, in quantities, which consists in placing them upon 
 a suitable support of a character that will not obstruct or only slightly obstruct 
 the passage of X rays, Rontgen rays, or any other rays penetrating matter 
 opaque to light ; placing the sensitized medium below the support and exposing 
 the objects and medium to the action of the rays; removing the support without 
 disturbing the positions of the objects and then developing the sensitized 
 medium, whereby a radiograph of the objects will be obtained, which can be 
 compared with the objects without disturbing them. 
 
 (2) In an apparatus for examining matters or objects in bulk, the com- 
 bination with a support for the objects, the said support being formed of mate- 
 rial readily penetrable by the rays, and having upon it a distinguishing mark, 
 made of material not penetrable, in combination with a means for producing rays. 
 
 (3) An improved tray, made of material which is of such quality and 
 dimensions as will permit objects to be placed thereon and readily radiographed 
 as though such tray had not been interposed between such objects and the 
 sensitized medium. 
 
 (4) The combination with a tray of canvas (c) and a rigid frame (a) to 
 which the canvas is stretched. 
 
 (5) The combination with the bottom and frame of a tray and a second 
 frame above the bottom, the said second frame being for the purpose of keep- 
 ing the matter which is examined a sufficient distance away from the first frame, 
 in order that the rays passing through such matter will fall clear of the first 
 frame and upon the sensitized medium. 
 
 (6) The combination with a conveyer and a frame of means for support- 
 ing the sensitized medium below the conveyer, and means for producing rays 
 and securing a radiograph upon the sensitized medium. 
 
312 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 (7) The use of a fluoroscope in connection with any form of device shown 
 in the drawings or covered by the preceding claims. 
 
 In addition to having to devise a special method, of which the above is a 
 description, it was necessary to adopt radiographic apparatus and materials 
 of such a nature as to make the methods and costs of the process commercial. 
 For instance, it was necessary to be able to make X ray exposures over a large 
 area in order to include sufficient oysters at an exposure, an area larger than 
 had been before attempted or rather required in the field of surgery, in which 
 I found the use of the X ray exclusive when I commenced my investigations; 
 also photographic material of a nature and cost suitable for the work had to be 
 sought. Without going into details, I may say that I overcame the various 
 difficulties, as I believe the accompanying exhibits prove. ° 
 
 PRACTICAL DEMONSTRATION OF THE PROCESS. 
 
 After considerable correspondence, I went to Ceylon to start my enter- 
 prise, and established my equipment on the island of Ipantivu, in the north- 
 western Province of Ceylon, and near to the famous pearl fishery of the Gulf 
 of Manaar. I have there invested in buildings, machinery, boats, ecjuipment, 
 and photographic supplies the sum of nearly $50,000, some of it my own money, 
 but most of it subscribed by different people in smaller or larger amounts, to 
 whom I or my friends had explained my ideas and the possibilities therefrom. 
 I proposed to get oysters when they were freshly fished, and instead of indis- 
 criminately killing all in order to get the pearls of value contained in the few, 
 to subject the oysters to the process. Those found to contain pearls of value 
 could be immediately opened; those containing small pearls of but little or no 
 value, could be planted under suitable conditions to remain until they had 
 become older and larger, and the contained seed pearls also larger and of value ; 
 while those found to contain no pearls could be returned to the sea either in 
 
 oThe following exhibits were appended to the manuscript submitted by the author: 
 
 Exhibit A, showing a part of the installation on Ipantivu Island — the water distilling building and 
 chimney, the process building, and bungalow. 
 
 Exhibit B, showing a panoramic view of the installation. 
 
 Exhibit C, showing coolies arranging oysters in trays. 
 
 Exhibit D, showing coolies carrying trays of oysters up to the process building to be subjected 
 to the X ray. 
 
 Exhibit E, a small radiograph of some growing oysters containing pearls. 
 
 Exhibit F, a small string of seed pearls. 
 
 Exhibit G, a radiograph of an oyster containing a seed pearl of a larger size and a string of pearls 
 of which Exhibit F was a part. Note the line down the center of the pearls showing the drilling. 
 Undrilled, in their natural state, these pearls would show up even more clearly. 
 
 Exhibit H, a part of a full-size radiograph showing some oysters containing small seed pearls. 
 
 Exhibit I, a full-size but onlypartly "fixed" radiograph of 120 oysters, showing number of tray 
 made by lead number thereon, and arrangement of oysters in regular rows by means of which the 
 oysters held on the trays are identified. The marks made by the inspector for seed pearls, large pearls, 
 or obscurity, or for other things are also shown. 
 
PROCESS FOR PRESERVING PEARL-OYSTER FISHERIES. 313 
 
 the hope that they would become inoculated with the pearl-inducing cestode 
 or at least to propagate and maintain the growth of oysters on the banks. 
 
 The immediate objects in view were therefore — 
 
 (i) The prevention of the theft of pearls from the rightful owners of the 
 oysters. 
 
 (2) A great increase in the yield of valuable pearls from a given number of 
 oysters. 
 
 (3) The maintenance of the yield of oysters from the natural beds, if not a 
 positive increase therefrom, as against the destruction of the fisheries under 
 present methods. 
 
 In actual working the radiographs are brought wet out of the process build- 
 ing, wherein all exposure and developm.ents are made in " dark-room " light, 
 and with good light and the wet radiograph practically nothing can escape. It 
 is easier to disclose that an oyster contains a pearl than actually to extract the 
 pearl. If the process errs, it errs on the side of safety. We find that we set 
 apart many oysters as containing seed pearls, which further examination shows 
 contain none, but that what was shown in the radiograph was an imperfection 
 in the film, an air bubble, a piece of coral outside the shell, etc. With practice, 
 even these mistakes can be eliminated, but they are not of such a nature as to 
 make us lose or eliminate an oyster which has the possibility of developing a 
 valuable pearl. With sufficient and proper help and auxiliary appliances, the 
 plant on Ipantivu Island, with its single tube equipment, can radiograph up to 
 400 oysters per minute. These thin-shelled, small Ceylon oysters (Margaritifera 
 vulgaris) are easy to handle. But we can attain just as much success with the 
 fresh-water mussels of the United States and other countries, and with the larger 
 Margaritifera maxima peculiar to Australia, Burma, etc. In fact my first experi- 
 ments were made on these. We can not, of course, do so many at a time or so 
 quickly, as they require a longer time of exposure, but on the other hand, the 
 product is of much greater value. My plant on Ipantivu Island has completely 
 fulfilled all expectations, and, so far as concerns the possibility of radiographing 
 pearl-bearing oysters on a commercial scale in order to disclose the contained 
 pearls and without injiu-y in any way to the oysters, has proved my process to 
 be a complete success. 
 
 Unfortunately, owing to certain conditions which arose after I came to 
 Ceylon and invested my capital, and which have prevented my getting live oys- 
 ters, I have up to now been unable to prove the next and equally important 
 stage of my process. However, as to whether pearl oysters known to contain 
 seed pearls can be kept under such conditions as will make them continue to 
 live and grow and thrive, and the majority of the contained seed pearls likewise 
 to increase in size and consequent value, I leave it to the members of the Inter- 
 national Fishery Congress to decide. 
 
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