As for as we know, connection between a ball lightning and caves hasn't been discussed till now. But it doesn't mean, that it doesn't exist. From one side, containing of great number of positive and negative charge of caves and as one of the forms of atmospheric electricity of a ball lightning from the other side [71], make observation of that connection natural and acceptable. I came back to the possibility of connection between a ball lightning and locality in my monograph " The appeal of abysses " [68]. In that book I described a field, situated in the North of Armenia, where ball lightning appear with surprisingly constant frequency.

In further years observation of a locality and additional materials gathered about the field spread new on the properties of that mysterious locality. The field is situated in the neighborhood of Lori region Odzun village. The field limited by a highway, farms of Odzun village and the canyon of Debet river. The surface of the field is ten hectare. The church with the name Saint Sign goes up to the edge of the field.

In direct neighborhood of the field, there are a lot of caves in the canyon ( Figure 68 ). Priests lived in caves in Middle ages.

Figure 68. The plan of the nearest to Odzun Saint Sigh church caves. A - caves of the ground floor, B - caves of the first floor.

Thickness of caves is big enough: 14 caves in the length of 60 m. It deserves attention, that caves are absent at all in a distance of several kilometers towards the South and the North from this part of the canyon.

This kind of big thickens of caves testifies that lava was rich with gases in that part, what causes big thickens of caves. There is a reason to suppose, that there can be in the depth of a rock. It becomes the subject of a direct problem in the depth of a rock.

In [68] monograph I supposed, that in that field the atmospheric electric unusual phenomenon - a ball lightning is connected with the peculiarities of the locality. I think, that those peculiarity is existence of caves in the neighborhood of the field and feasibility of closed caves existence under the field. As soon as, caves contain appreciable quantities of negative ions and negative ions are famous for their medicinal properties [20], those facts, which we managed to collect about that field become comprehensive.

The field is called Invigorating. It has the unusual medicinal properties and it is especially sanitary for wounds. According to the tradition, which is written down in Odzun village, medicinal properties of the field were discovered in the

4^th century B. C. Due to the tradition, before starting the expedition Alexander of Macedonian left wounded soldiers on that field, thinking that they were heavily wounded all the same and their death was undoubted. But some time later, soldiers of Macedonian, coming back from the expedition, which was not success, found out with surprise that their friends recovered. Being interested in that, they elucidated that the reason of the wounded people's unbelievable recovery was the field. Since that day the field is called Invigorating.

The second group of the facts is related to the connection, existing between the field and ball lightnings. The field is famous for appearance of ball lightnings with great frequency there. During the last hundred of years, at least tens of inhabitants of Odzun died because of the contact with a ball lightning on that field.

A ball lightning is one of the rarest phenomena of nature and probability of its appearance in one minute in a distance of 1 km² is 1.10^-9 [72],[3]. If we calculate the sizes of the Invigorating field ( 300 . 300 m² ) and the number of ball lightnings victims during the last hundred years, possibility of a ball lightning appearance on the Invigorating field will form ~1.10^-6. It is thousand times bigger than feasibility of a ball lightning appearance in an accidental place. We think, future investigations of caves and the Invigorating field will give new dates, confirming the connection of caves and ball lightnings.