Tesoro Cortes
Gordon Bailey
| At last the long wait through summer was over, and some of the fields where I have search permission were starting to be harvested. The first field to become available had only recently been cut and was still in stubble, but fortunately the remaining stalks were quite short. It did not take long to get back into the familiar routine, and within a few minutes I had started to recover the usual bits and pieces of scrap lead. A few yards further on, though, I recovered something totally different, a hammered silver sixpence of Charles I. As this was the first hammered coin I had recovered for this season it brought something of a warm glow, and I placed it into my padded tobacco tin for sake keeping. At first glance it appeared to be very “spend worn” but close examination proved this not to be the case. Most of the wear seemed to have occurred from the coin being rolled around in the soil during ploughing. I decided to concentrate on the immediate area just in case the coin was not a casual loss. Due to the recent rain the ground was very soft and easy to dig, but it was also darker and more friable than the usual Essex clay on most of my sites. My next find was laying on the surface and was a small mid-18th century breech buckle, unfortunately with its centre missing (Fig. 1.). Everything seemed to be going well until I recovered a large homemade lead weight. The signal from this was very “iffy” and my first impressions were that the detector was indicating a tiny fragment of non-ferrous scrap just under the surface. Such was not the case, and the target proved to be a 4oz lead weight located at a depth of 10in. I felt that such a large object should have given a far clearer signal, and I re-buried it a few inches down where it gave a loud response. |
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I also recovered a number of buttons, all of 18th century date, including a lady’s livery example (Fig.2.). A buckle also came up amongst the buttons, this being a 17th century type that was quite ornate but had been fitted with a replacement pin (Fig.3.).
One deep target that I did find was a lead leather worker’s palm guard. These all seem to be of a fairly standard size, averaging about 4in in length.
During my search I recovered around 40 items, but apart from the finds mentioned above, nothing came up of any great interest.
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| Fig. 1. | Fig. 2. | Fig. 3. |
The detector concerned, the Tesoro Cortes, was the first detector that I have ever field tested with an LCD read-out. In the past I have had little confidence in such machines. I know that there are many readers out there who swear by them and have come up with some great finds by using them. However, I have always worked on the principle of “when in doubt dig” and I did not see how a LCD display could provide any benefits over the equipment I was already using.
When I first got to see and handle the Cortes I must admit that I was impressed. It had the same size and type of coil I have fitted to the Tesoro I normally use. However, the control box was only about half the size of that on my own detector, including the meter. On the Cortes, the batteries are no longer housed in the control box, but are in a compartment below the armrest. This helps in the balance of what is already a lightweight machine. The detector also breaks down into three short pieces, which is helpful for normal transportation and perfect if you are planning to take it on holiday.
My intention for the first outing was simply to acquaint myself with its performance, peculiarities and controls; after that I felt that searching could begin in earnest. I set discrimination at the position halfway between zero and iron. This eliminated all unwanted targets up to the size of 6in bolts. The setting worked very well in the first area I searched, which I knew to be contaminated with lots of small pieces of iron along with some larger pieces.
The search area was chosen deliberately, as I had detected over it many times in the past and it could be described as “very well hit”. I doubted that there would be a single non-ferrous item remaining to be found, but was quite shocked when - within a short time of switching on - I recovered three large musket balls and a small medieval buckle.
The Cortes managed to eliminate the smaller pieces of iron without any trouble and when the larger pieces came through on the audio, the LCD gave a reading of “Iron or Foil”. Naturally, I dug up all such targets to make sure that the detector had identified them correctly; in every case it had.
My next concern was the term “Foil” that came up on the meter. The conductivity of foil is very close to that of medieval hammered silver coins, which are obviously not found in America where the detector was manufactured. I therefore dug each foil signal to once again make sure that what I was being told was correct.
By the end of my first search I was feeling confident that success on future outings would depend on myself rather than in any shortcoming in the equipment I was using.
On the following day I returned to the stubble field mentioned in the opening paragraphs. I was confident that I had searched this fairly thoroughly, and while conscious of the fact that it is always possible to miss the odd item, I did not think that I had missed very much. I returned directly to the area where I had found the Charles I sixpence and therefore, on my last visit, had given a particularly methodical search. For some reason the seeds from last season’s sowing had not taken on this patch, and I was therefore searching flat soil that remained void of crops. However, the whole area was covered with filled in holes from my last visit.
From the first target recovered I became concerned at what I had missed previously. This find was only inches away from where I had recovered the sixpence and was a crotal bell, admittedly buried at some depth. Within the immediate area I recovered a further five targets comprising a broken spur, a spindle whorl, and three copper coins. At this point it dawned on me that I had not missed these targets, it was just that they were out of range of my normal machine.
The remainder of the field was still covered in stubble, the stalks being a minimum of 6in tall and in some areas a lot higher. I decided to continue searching the rest of the field, but in view of the stubble expected only surface finds. This conclusion was to prove quite wrong. Initially, I used the search coil to push the stubble down but this was exhausting work and I gave up eventually and just skimmed the head over the top.
I recovered quite a few targets but these were in the main pieces of lead, with the odd worn copper coin thrown in. I had started off in the hope that there would be some targets near the surface, but I needn’t have worried too much for even with the spacing off caused by the stubble the Cortes was still making recoveries well into the soil.
Over the next few days all of the sites I visited were still covered with stubble, but fortunately two of the fields had been planted with corn and the stalks were soft allowing me to get nearer to the ground surface.
The first of these fields had not been a busy one in my previous searches and, fact, could be described as close to barren. However, I thought this would be a good test for the new detector.
For the first 10 minutes the Cortes did not register even so much as a whisper, but then came a double signal. At first I thought I had found a large piece of iron, for there was no difference in the audio. However, the read out was good so I concluded that I must have located two targets and this proved the case. The first find was a very small pewter button, but only a few inches away from this was a groat of Henry VII (Fig.4.).
This naturally caused me to stay in the area for some time and conduct a careful search, but nothing further of interest came to light. It then dawned on me that although I had found nothing of worth since the groat, I had been digging up numerous targets. At this stage I stopped, emptied my finds bag and made a count. Since finding the groat I had recovered 20 pieces of non-ferrous, all from what I had previously thought to be a dead field.
I also realised that I had become carried away with my own detecting experiences and was not paying proper attention to what I should be doing - testing the detector. Fortunately the field is a fairly small one and I therefore went for a “walk about”. From previous searches I knew that there was one patch of the site that is heavily infested with nail and small pieces of iron and I made for this. As I approached the area I increased the discrimination up to the iron mark. My search here was more to see how the Cortes would cope with such conditions than the hope of any finds; in fact, in the past I had made it a point to avoid this area.
The first response came from a very large piece of iron and the read out on the meter indicated “Lift Coil”. The Cortes is a powerful, deep-seeking detector and this facility is provided to deal with signal overload. I lifted the coil as instructed and the meter flickered between iron to coin, and back to iron again. When I investigated the target it proved to be a huge piece just below the surface; in was so big, in fact, that I left it where it was rather than attempting to carry it to the nearest ditch. I doubt if any detector available today could be certain of the identity of this target (unless it had a magnet on the end of it!).
A yard or so from the iron the detector gave another loud signal. This time, however, the meter remained nice and stable with the number on the right being high. Although I expected a surface find the target was some 12in down and was the crotal bell shown in Fig.5.
By now I knew that I could rely on the meter should the need arise. This did help me out a few times during my search as some signals came through as positive on the audio but were identified by the meter as iron. The reason for this was that I was working at a very low discrimination setting where large iron tended to come through as positive on the audio. It is possible to wind up the discrimination to eliminate such iron altogether and no audio comes through, but I prefer to work at lower settings and tolerate the occasional iron signal.
Eventually I decided that I had recovered most of the finds available from this site and I decided to make my way back to the car leaving the detector switched on. I was about halfway through the walk when the Cortes gave another signal. As with that produced by my other finds, this was once again very loud and positive. For some reason the soil in this area seemed to be particular hard and it took some time just to crack through the surface. (It is on occasions such as this when I think that a small JCB would sometimes come in handy!). It took me about five minutes to dig down about 12in at which point I could see a lump of oxidised lead. My first thoughts were that all my efforts had been for nothing, but on retrieving the lead from the hole I soon changed my mind. What I had actually found was a 12th century vesica-shaped lead seal matrix in nice condition (Fig.6.). On my return home I was able to read the inscription s/walter son of simon cerol.
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| Fig. 4. | Fig. 5. | Fig. 6. |
This more relaxed search mode - where I was no longer worrying about taking note of how the Cortes reacted to certain targets and the read out it gave - seemed to have helped. Within a short space of time I had found a silver penny of Edward I somewhat battered by many centuries of being in the soil. I had some concern that the meter might indicate small hammered coins as “foil”, their conductivity being similar; but such was not the case as this coin proved.
My final mop-up operation proved that I had not missed too many targets, and where this was the case I felt it to be down to human error rather than any failings in the detector.
Apart from the odd bits of lead, there were two finds that made my final search worthwhile. One was a heavily cast Tudor thimble, and the other a William and Mary copper halfpenny.
I would have liked at this point to have tried the Cortes out on ploughed land, but all the fields available were still in stubble.
The next field I tried had yielded numerous Georgian buttons and the odd copper coin in the past, but nothing earlier than this period. Whether the next find was down to fate, luck, the x-factor, or an innate dowsing ability I don’t know. I walked onto the field and turned on the detector. The screen read “Lift Coil” which I did. As I brought the coil back to the ground it gave a loud signal that resulted in a threepence of Elizabeth I dated 1573 (Fig.7.). In all my years of detecting this was the quickest time of starting a search before finding a hammered coin.
So far, in performance terms, the Cortes was living up to the claims made by its manufacturers. However, I also like to assess whether there is any scope for improvement in the actual physical design and construction. As stated earlier, the detector is very lightweight with a small compact control box, three-piece stem etc. The only alteration that I would like to see concerns the jackplug socket. This is currently situated at the back of the control box, but I would have preferred to see it at the top of the shaft near the battery compartment. In the later case the headphone lead would be less likely to get caught up, and there would be less strain on its connections.
There is a warning in the instruction booklet that if you use this detector you should be prepared to dig up some deep targets. Within reason it is possible to judge the size of the target, but not necessarily its depth from the read out on some types of objects. However, if you feel this facility to be important it is possible to keep raising the coil until the target ceases to give a signal and from this it will be possible to assess the depth at which it is buried. One such target I encountered was a purse bar missing its loop (Fig.8.), which gave a large signal due to its length.
By now I had found two items predating the 18th century. I found that particularly encouraging when taking into account that I was still searching in stubble. I also have to say that the coil was totally unaffected when it was used in stubble. There are some detectors that give a false signal should you hit a particularly resistant stalk, and this can be frustrating, as you have to keep stopping to check whether or not they are phantom responses.
As in past searches I was recovering small pewter and copper buttons, but it was not until I stopped to take a drink from my flask that I realised just how many I had found. I had only one occasion to dig iron, but this was a ploughshare and any machine could be forgiven for that oversight.
As I continued my search I felt that I had been using the Cortes for years rather than days. This was a good feeling for now instead of just testing the machine, I was using it as it should be used with great confidence.
Another hammered coin soon came to light, this time a penny of Edward I London Mint. My thoughts at this point were that if I am recovering this amount of material from a stubble field, then how much could be found once the site had been ploughed and rolled.
On returning home I counted the final button yield that came to 20, and one of these, when cleaned, proved to be silver (Fig.9.). I had also found 12 copper coins, all of 18th century date.
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| Fig. 7. | Fig. 8. | Fig. 9. |
As with my previous solo outings, freshly harvested fields were the only ones available, and stubble is one of his pet hates. I seemed to be doing reasonably well at making the odd find, but I noticed he kept looking over to see how I was getting on. Due to the height of the stubble the coil seemed to bounce over it, and this meant trying to use the coil to force it down. As a result the search was rather hard going. However, this did not stop finds being made. One that I found particularly pleasing being a bronze weight of Henry VII or VIII. Two other items of interest came to light one being a 17th century spur buckle, and the other a lead harness decoration dating to the 18th century. At the end of the search we compared the amount of targets found: my partner had unearthed six, while I had recovered 42; his expression said it all.
At long last there was movement on the fields, and the tractors seemed to have come out in force. This involved the decision of where to search first. Some fields had been ploughed but not rolled, while others had been just raked and these seemed the most tempting. I had not previously searched some of the fields now available so it was something of a gamble as to whether they would prove busy in finds or not.
The Cortes can be used in “All Metal” so far as audio is concerned, while the meter will still provide discrimination and prevent the digging of unwanted targets. This allowed me to decide if an area of the fields had seen activity in the past, for if pieces of ferrous metal are present in number then non-ferrous items should also put in an appearance.
After a while I located an area that seemed to be busy. I therefore changed back into normal search mode and moved the discrimination dial to just below the iron mark. The chattering coming from the pieces of iron now ceased, and the only time audio signals came through were those from non-ferrous items such as buttons etc.
One of the first items recovered came up from quite a depth; this was a horse brass from a blinker carrying the initial “D”. My next find jumped back 400 years in time, taking the form of a sovereign type penny of Henry VII, with the letters “DR” by the shield and a mitre above.
As an experiment I turned the discrimination down to hear how many bits of iron the machine had to contend with while still being able to locate good targets; the great amount of “chatter” I heard was most surprising. Returning the dial to where the numerous unwanted signals ceased I continued my search.
I normally avoid searching near hedgerows because of the amount of shotgun cartridge caps, but in this case the strip of field looked inviting and I decided to give it a try. Although the cartridge ends were present, as I had expected, from in amongst them came some interesting finds. The first of these was a small 18th century shoe buckle (Fig.10.), then came a jaws harp (Fig.11.), followed by a medieval strap end fork type buckle (Fig.12.). I also recovered a surprising amount of modern coinage, most likely lost by shooters or walkers. The most modern item found was a pewter figure of a shooter in his plus fours (Fig.13.), and the oldest an antoninianus.
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| Fig. 10. | Fig. 11. | Fig. 12. | Fig. 13. |
With my normal detector I usually use it hip-mounted, which makes it light and easy to operate. From lengthy outings with the Cortes, I found that it is so light and well balanced that it is virtually the equivalent to my normal detector in hip-mount mode.
This outing was to be the one that yielded the most finds although not all were of great interest, taking the form of worn copper coins, lead weights, and buttons. However, I did recover a further hammered coin, this being a half groat from the Commonwealth period. Then came a find that proved a bit of a heart stopper, or at least initially. When I recovered this item it was still encrusted in soil and all I could see was the glint of gold. But as I began to remove the dirt signs of copper could be seen, and the glint I had seen originally came off its gilding of which it has about 90% remaining. The item, which is shown as Fig.14., is a fleur de lys, and I would estimate that it dates to the 15th or 16th century but as to its use I am uncertain. The reverse is gilded in exactly the same way as the obverse and this implies that it was meant to be seen. The attachment, or part of it, is a horizontal bar and it is possible this could have had another fleur de lys or similar decoration fixed to it.
After this surprise came something of a run of buckles including two 17th century broken spur types, a small medieval buckle, and finally one 15th-16th century type. Although I had set myself the task of searching along the line of the hedgerow, occasionally I had an intuitive feeling to wander out further into the centre of the field. This produced two hunting buttons, recovered within a few inches of each other, and two livery buttons that again came up quite close together. These finds were followed by numerous copper farthings and halfpennies. On my return home I had a count up of the non-ferrous finds recovered and this came to 54; I was therefore more than pleased with the results of my search.
To maximise search time I mainly search within my home county, but I have searched on areas outside of this in the past. As my testing was still continuing with the Cortes, I thought it might be useful to revisit some of these farms as I know that soils and mineral content can vary from county to county. There was one field that had been searched by numerous other detectorists and myself in the past and I thought that this might be worth a try; however, as a result of the previous intensive searching I did not expect to find very much. The site had just been ploughed and rolled, which was an added bonus. The reason for the interest in this field was that it had produced Roman finds in the past. However, these had been in the main small bronze coins, the odd brooch, and other broken bits and pieces.
After the first hour I began to feel that my time would have been better spent searching closer to home for all that had come up was one small Roman bronze coin, admittedly in fairly good condition. A short time later I recovered what was a pleasing find for me, the largest complete crotal bell that I have ever found to date (Fig.15.). This was also the deepest find unearthed during the testing of the Cortes but well worth the effort. Although some of the pattern had been worn away, the maker’s mark was still clear this being the letters “MS” with the number “6” below.
Apart from the two interesting finds mentioned, as the day progressed little else came to light apart from the odd button and musket ball.
Just when I thought my luck had deserted me came a final find from almost the same depth as the crotal bell. This was a Roman bronze figurine, in beautiful condition, representing the god Mars (Fig.16.). These days it does take quite a bit for a find to excite me, but this was one of the best finds I have made for many years. It didn’t even have so much as a scratch and when I had returned home and was washing it the true degree of workmanship shone through. The helmet of Mars rested on the crown of his head and even this had a face depicted on it. The plumage of the helmet was finely detailed, as was the armour around the shoulders.
In conclusion, I have to say that although over the years I have had the privilege to test some great detectors, in my view this has been the best so far. My finds rate has increased dramatically, and previously worked out sites have once again become productive. If you are wondering whether I intend to include the Cortes in my armoury I have to say “No”. For the future it will be my armoury.
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| Fig. 14. | Fig. 15. |
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| Fig. 16. |
The Tesoro Cortes has seven main controls besides its LCD display meter. These consist of four rotary controls and three flick switches. The function of each of these controls is described below.
On/Off Sensitivity: This control switches the detector on and off, and allows for adjustment in sensitivity levels. The Sensitivity knob is used to raise or lower the power to the operational amplifiers, which change the gain. Gain is a measurement of how much a signal is amplified. The higher the gain the more depth and sensitivity to small objects that a detector has. Unfortunately, any small interference that is amplified can cause a detector to become erratic. The Sensitivity control is therefore used to find the best setting in any location without the detector becoming erratic. For most English inland sites this control can be set to around “9”, but should be lowered if spurious signals are encountered.
Mode: Three position flick switch. “Disc” is the normal search mode. Left, in a spring-loaded position, is “Sum” mode. This is a multi-tone ID system that averages all readings if the coil passes over a target. This is a facility that I did not find useful, and preferred to use my own judgement on the information provided by other modes. The right position of the switch is “All Metal”. This mode is used to help pinpoint or to handle very highly mineralised ground (the Cortes uses a factory preset ground balance in the Discriminate mode).
Discriminate Level: Applies to the audio signal only, the display will still provide information. For most arable fields I found the ideal setting to be somewhere between “0” and “Iron”. Keep this control as low as site conditions allow.
Threshold: Applies only to the “All Metal” mode, and should be adjusted until you hear a slight but steady hum.
Ground Balance: Applies only in the “All Metal” mode, and is adjusted so that when lowering the search coil to the ground no change in threshold is heard.
Light: Back lighting of the LCD display enables searching in darkening conditions. A flick switch provides the choice of “Low” or “High” depending on the ambient light. Use only where necessary, as it will reduce battery life.
Notch: A three-position flick switch, the centre position being default, no notch. This facility will not be necessary when searching most inland farm sites. When using notch the regular Discrimination Level should be turned to zero. Turned left to “Narrow” the notch covers most pull tabs; turned to “Wide” it will eliminate most pull tabs and screw caps.
LCD Display Meter: This performs a number of functions. First of all it provides a continuous display of the battery level, by means of a bar graph to the right of the meter. The display also shows a readout of the likely target identity but as the instruction manual warns: “A target identification meter is never 100% accurate. If you get a strong, positive signal when hunting, dig it, no matter what the display shows. Digging the good audio/bad display target will result in better finds over the long run than ignoring those signals.”
The top row of the display shows the target data in the broadest terms. All targets will fall within one of four categories: Iron or Foil; Nickel, Pull Tab, Ring; Screw Cap; and Silver Coin, Copper Penny. However, the lower row provides much more detailed information.
In the lower left segment of the display is Coin Depth, shown in inches. In the centre of the row is a nine-segment bar showing all the information the detector saw during the entire coil sweep. Finally, between the graph and the battery indicator is the ID Number. The ID Number shows the peak part of the signal as a two-digit number between 0 and 95. Iron reads as 0 and copper and silver coins read as 95. All other targets read somewhere in between. The best distance from the coil is somewhere between 4in and 8in. If the coil is closer a meter indication will suggest “Lift Coil”. Moving the coil slightly away from the target in such situations will result in a more accurate reading.
The Tesoro Cortes is available from Joan Allen Electronics Ltd, 190 Main Road, Biggin Hill, Kent TN16 3BB, UK. Telephone: 01959 571255, Fax: 01959 576014, E-mail: sales@joanallen.co.uk. Order online by credit or charge card at Joan Allen's main Tesoro product pages by clicking here!
Visit the Joan Allen web site at http://www.joanallen.co.uk.
© Reproduced with kind permission of Treasure Hunting Magazine.