Notice of the time, place and purpose of any Special Meeting of the Board of Directors shall be given at least five (5) days previous thereto, by written notice, delivered personally or mailed, to each Director at his last known address. If mailed, such notice shall be deemed to be delivered when deposited in the United States mail so addressed, with postage thereon prepaid. The attendance of a Director at any meeting shall constitute a waiver of notice of such meeting, except in case a Director shall attend a meeting for the express purpose of objecting to the transaction of any business on the grounds that the meeting shall not have been lawfully called or convened.